Warren Zev Harvey
The Hebrew University of Jerusalem
Harry Austryn Wolfson (1887-1974), the eminent Harvard historian of philosophy, published his magisterial Crescas’ Critique of Aristotle in 1929. It is arguably the most important scholarly work on Jewish philosophy published in the modern era, and remains today a shining example of formidable erudition, superb philological skill, highly perceptive philosophical interpretation, and felicitous analytic writing. In this work, Wolfson analyzes Rabbi Hasdai Crescas’s (c. 1340-1410/11) critique of Aristotelian physics, explains its role in the revolution of modern science, and portrays his “new conception of the universe.” While Wolfson duly presents Crescas within his medieval milieu, he is also interested in him as an original philosopher who is relevant to our contemporary concerns. In my following remarks, I wish to try to understand Wolfson’s pragmatic Crescas. How did Wolfson, as an undergraduate student at Harvard, become interested in Crescas, and in what way did he consider him to be important to modern philosophy and modern philosophers?
The Pragmatic Movement May Find its Visions Foreshadowed in Crescas
Born in the Lithuanian town of Ostrin (= Austryn), Harry Wolfson studied at the renowned Slobodka Yeshiva, and at the age of 16 immigrated with his family to the United States. In 1908, he enrolled as a freshman at Harvard University, one year after the retirement of William James (1842-1910), and he remained there all his life. He was at first more interested in Hebrew literature than in Jewish philosophy, publishing poems and essays in Hebrew during the years 1908-1911. He majored in Semitics, studying with George Foot Moore (1851-1931), David Gordon Lyon (1852-1935), and James Richard Jewett (1862-1943). It was George Santayana (1863-1952) who drew him toward philosophy. Studying with Santayana, he was captivated by American Pragmatism.
Wolfson’s first published philosophy essay, “Maimonides and Halevi: A Study in Typical Jewish Attitudes towards Greek Philosophy” (1912), was written originally for one of Santayana’s classes. It is in this remarkable essay that Crescas was interpreted by Wolfson as a forerunner of Pragmatism.
The essay contrasts two “typical attitudes” toward Greek philosophy among medieval Jews: the “Hellenizing” one, represented by Moses Maimonides, and the “Hebraizing” one, represented by Judah Halevi. Maimonides was “a true convert to Aristotelian philosophy,” whereas Halevi was a skeptic, “full of doubts about the truth of Aristotle’s theories.” Maimonides was “ruled by reason,” Halevi by “feeling and sentiment.” Maimonides was a “rationalist,” Halevi an “empiricist.” Maimonides was the author of the Guide of the Perplexed, “a formal, impersonal treatment of his philosophy,” and he was also a legalist, author of a “codification of the talmudic Law.” Halevi was the author of the Kuzari, written “not more scholastico” but in a “spontaneous” dialogue form “in the fashion of Job,” and he was also the author of “synagogal hymns of highest lyrical quality.” Wolfson’s essay is unabashedly partisan: he is a “Hebraizer,” lauding Halevi’s “Hebraism” and loathing Maimonides’ “Hellenism.” He treats Halevi as a hero and Maimonides as a renegade. In his more mature researches, Wolfson would jettison these caricatures of Halevi and Maimonides, but surely such partisanship can be forgiven in an undergraduate.
Wolfson fervidly argues in the essay that the spirit of Hebraism, found in Halevi, adumbrates contemporary American Pragmatism. If the Greek focus was on theory, the Hebraic focus was on action. Throughout his essay, Wolfson quotes Halevi’s Kuzari. However, in his concluding arguments, he suddenly—without warning—turns to Crescas and quotes his Light of the Lord instead of the Kuzari. Thus, he writes:
Finally, the philosophers place speculation above action because they consider speculation as the greatest, the only self-sufficient happiness. But speculation can afford man no happiness unless it has its basis in action, unless it has been called forth by some practical motive. In order to derive intellectual pleasure from seeing things as they are, there must first be a problem, a difficulty in seeing those things. Intellectual pleasure consists in the transition from a state of perplexity to that of certainty, in the unraveling of a problem, in the suspense and repose we experience after a state of confusion. “The pleasures of our life consist in the getting of things we desire; and the desire for a thing consists in our being potentially in the possession of that thing but actually deprived of it.” We can have no intellectual pleasure unless we are conscious of its coming.
The text quoted in this passage, as Wolfson informs us in his notes, is from Crescas’s Light of the Lord, II.6.1. Intellectual pleasure, like any other pleasure, is not, as the Aristotelians thought, something in actu or static, but rather is something dynamic: it is not intellectual cognition in itself, but the transition from potentiality to actuality—from potentially knowing to actually knowing. “The pleasures of our life,” wrote Crescas, “consist in the getting of things we desire” (le-hassagat ha-dabar ha-nikhsaf), not in the possessing of them. Pleasure is not having no problems, but rather it is the process of “the unraveling of a problem.” It is problem-solving, and “[i]n order to derive…pleasure…there must first be a problem.” There must first be some practical motive, for “[s]peculation can afford no happiness unless it has its basis in action.”
Wolfson continues, quoting again from the same chapter of Crescas’s Light:
We all take pleasure in our senses, and yet it is not those permanent sensations impressed upon us by external forces that give us the greatest pleasure, but those sensations which we ourselves bring upon us by intention and desire. The mathematician may take pleasure in solving problems, but certainly not in the self-evident truth of the multiplication table. “We see this in the fact that we do not take pleasure in the comprehension of self-evident truths. The reason is because there was no transition from potentiality to actuality, and hence there was no desire to comprehend them.” Intellectual pleasure, then, cannot result but from a problem; but how can you have any problem if you have no practical interest in the world, if you already had conquered it, and are going to live in it on mere contemplation?
The pleasure of the mathematician, like all pleasures, is in problem-solving, in the transition from potentiality to actuality. We do not take pleasure in our knowledge of self-evident truths (prima intelligibilia), explains Crescas, since their knowledge does not involve the transition from potentiality to actuality. Wolfson states his moral clearly: the Greek philosophers who devote themselves exclusively to the vita contemplativa cannot enjoy true pleasure, for they have “no practical interest in the world.” The Hebraizers, like Halevi and Crescas, and the Pragmatists, like Santayana and Wolfson, are able to enjoy pleasure because they are interested in the world. Wolfson now writes:
With this Halevi’s criticism of philosophy is completed. His general point of view…is Hebraic.…Halevi’s [thought] is old wine that is even now bursting new bottles. Contemporary thought, the whole pragmatic movement, may find its visions foreshadowed in Halevi’s discussions. [The Kuzari] must now be considered the most logical of mediaeval expositions of the practical spirit as contrasted with the speculative.
Although Wolfson writes “With this Halevi’s criticism of philosophy is completed,” in fact the “this” refers to the two quotations from Crescas cited above. In other words, it is with Crescas that Halevi’s criticism of philosophy is completed. The wine that is bursting the bottles is Crescas’s wine. In young Wolfson’s judgment, Crescas continues and completes Halevi’s pragmatic project. Already as an undergraduate, Wolfson may have been beginning to suspect that “the most logical of medieval expositions of the practical spirit as contrasted with the speculative” was not Halevi’s Kuzari but Crescas’s Light of the Lord.
One day in March 1912, David Gordon Lyon asked Wolfson, “Suppose you were awarded a fellowship, what would you write about?” Wolfson replied inadvertently, “A literary essay on Crescas.” He received the fellowship, and he soon found himself traveling across the Atlantic to peruse manuscripts in the great European libraries. He returned after two years to Harvard, wrote his doctorate on Crescas (1915), and published his Crescas’ Critique of Aristotle. It seems that his interest in Crescas was not aroused by the medieval rabbi’s revolutionary physics, but by his proto-Pragmatism.
To Students of Bergson Crescas May Be of Interest
If during Wolfson’s student days the avant-garde philosophy in the United States was Pragmatism, the avant-garde philosophy in France was that of Henri Bergson (1859-1941). Bergson’s L’Évolution créatrice appeared in 1907 and had a powerful impact in Europe and beyond. William James praised Bergson highly in his essay, “Bergson and the Critique of Intellectualism” (1909), thus endearing him to American Pragmatic philosophers. Twice Wolfson drew attention to an analogy between Crescas’s theory of time and that of Henri Bergson. The first mention of Bergson was in Wolfson’s 1919 essay, “Note on Crescas’ Definition of Time”:
To students of Bergson…it may perhaps be of some interest to compare his distinction between “pure duration” and “mixed time” with the implications of the two contrasting definitions of time which we have discussed [i.e., Crescas’ definition of time in terms of duration and Aristotle’s definition of it in terms of motion].
The second mention of Bergson was in a parallel passage in Wolfson’s Crescas’ Critique of Aristotle:
Crescas’ counter-definition divorces the idea of time from that of motion.…According to this new definition, the essence of time is not motion but duration.…Students of Bergson…may perhaps find in [the opposition of Crescas’ and Aristotle’s definitions of time] some suggestion of his distinction between “pure duration” and “mixed time.”
In his Light of the Lord, I.2.11, Crescas defined time as “the measure of the hitdabbequt of motion or of rest between two instants.” The Hebrew term hitdabbequt reflects the Greek synechés and the Arabic ittiṣāl, and it is literally translated as “continuity,” “continuousness,” or “continuum.” Wolfson translates Crescas’s definition as “the measure of the duration of motion or of rest between two instants.” He explains that in the history of philosophy dating at least from Plotinus, there have been two distinct definitions of time: the Aristotelian definition of time in terms of motion and the non-Aristotelian definition of time in terms of duration. He cites many examples of the non-Aristotelian definition in Greek, Arabic, Hebrew, and Latin philosophy, including some Latin texts that in fact use the term “duratio.” Nonetheless, his controversial choice of “duration” as the translation of Crescas’s hitdabbequt was no doubt influenced in part by Bergson’s theory of time as duration.
In any case, Wolfson was of the opinion that the distinction between the theories of time of Crescas and Aristotle foreshadowed in some way the distinction in Bergson’s philosophy between duration (la pure durée) and mixed time (le temps mixte), that is, time mixed with spatio-physical concepts.
Wolfson describes Crescas’s conception of time as follows: time “is the continuity and flow of the activity of the thinking mind”; it “is purely ideal”; its “essence [is] pure duration.” Wolfson’s invitation to compare Crescas’s concept of hitdabbequt with Bergson’s concept of la durée is suggestive and definitely worth pursuing. The comparison might be fruitful not only because of the fascinating similarities that would emerge in the theories of time of the two philosophers, but, more importantly, because of the provocative differences. For example, Bergson insisted that real time is intuited, experienced, and lived, but never intellected (nous ne pensons pas le temps réel), whereas Crescas held that time is known by the intellect (yuskal). Related to this, Bergson insisted, against Nietzsche, that time, unlike space, is heterogeneous and non-recurring, whereas Crescas held that time, like space, is homogeneous. Crescas’s theory is more scientific and less metaphysical than Bergson’s. I have little doubt that if he could have been present at the celebrated 1922 debate between Einstein and Bergson, he would have sided with the physicist.
The Mysterious Element of Impregnation
Although his Crescas’ Critique of Aristotle predominantly treats problems in medieval physics and is thus of interest primarily to erudite historians of science, Wolfson also sought to discuss religious subjects whenever appropriate. As he argues in his early essay “Halevi and Maimonides,” the Hebraic sentiments of Halevi and Crescas had an affinity to the Pragmatic movement. Moreover, some leading Pragmatic philosophers, like James and Santayana, appreciated religion and in particular mystical experience.
One unforgettable passage in Crescas’ Critique of Aristotle concerns the “Element of Impregnation.” In Light I.2.1, Crescas presents a striking exegesis of Isaiah 6:3, which is translated as follows by Wolfson:
This last metaphor [“Place” = God] is remarkably apt, for as the dimensions of the void permeate through those of the body and its fullness, so His glory, blessed be He, is present in all the parts of the world and the fullness thereof, as it is said, ‘[Holy, holy, holy is the Lord of Hosts], the whole earth is full of his glory’ [Isaiah 6:3], the meaning of which may be stated as follows: Though God is holy and separated by a threefold holiness, alluding thereby to His separation from three worlds, still the whole earth is full of His glory, which is an allusion to the element of impregnation [yesod ha-ʿibbur], which is one of the elements of Glory.
The Rabbis referred to God metaphorically as the “Place” of the world (e.g., Genesis Rabbah 68:9). Crescas illustrates this metaphor by referring to Isaiah 6:3. According to his exegesis, God is transcendent (“holy, holy, holy”) but also immanent (“the whole earth is full of His glory”). As the three dimensions of the infinite vacuum permeate the entire universe (that is, the infinite vacuum is the place of all physical objects), so God’s omnipresent glory permeates all parts of the world and the fullness thereof (and so God is thus called the “Place” of the world). This is “an allusion to the element of impregnation” (yesod ha-ʿibbur). But what is this “element of impregnation”?
Now, the phrase “yesod ha-ʿibbur” (element, principle, or foundation of ʿibbur) is not unknown in Hebrew literature. It refers primarily to the “principle of intercalation” of the calendar, the term ʿibbur (impregnation) having acquired the additional meaning of “intercalation” in Rabbinic Hebrew (cf. BT Sanhedrin 10b-11a). For example, Rabbi Abraham ibn Ezra (1089-1167), in his book on the calendar, Sefer ha-ʿIbbur (“Book of Intercalation”), writes in his introductory poem that he will provide “the calculation of the principle of intercalation (yesod ʿibbur) for all generations.” Again, Rabbi David Abudarham (14th century), in his famous work on Jewish liturgy, included a discourse on intercalation (seder ha-ʿibbur) and subtitled its introduction “To Know the Principle of Intercalation” (la-daʿat yesod ha-ʿibbur). However, such a calendrical usage makes no sense in the context of Crescas’s passage. The term ʿibbur (impregnation) is also found in the Kabbalah, where it usually refers to the transmigration of souls, but this usage too makes no sense in the context of Crescas’s passage. Wolfson therefore gives the term ʿibbur a different Kabbalistic meaning. It refers, he explains, to the cosmic emanative process. His interpretation, based on various texts from the 13th-century Girona Kabbalists, is brilliant and stimulating. He explains his interpretation thus:
Crescas uses the expression yesod ha-ʿibbur, the element of impregnation, as a designation of the emanative process whereby the Divine influence is extended to the terrestrial world. Ordinarily…the term ʿibbur refers to metempsychosis, as in the expression sod ha-ʿibbur [“the mystery of impregnation”].…
Crescas’ interpretation of the verse [Isaiah 6:3], therefore, is as follows: Though God is exalted above the three worlds into which the Sefirot are divided [i.e., the worlds of mind, soul, and body], still through the emanative quality of His Glory, i.e., the [ten] Sefirot, He is present in the terrestrial world.…
[T]he term yesod in Cabala is the name of the ninth Sefirah [= Foundation] which… represents the genital organs. Cf. [Rabbi] Azriel [ben Menahem of Girona]…: yesod ʿolam be-khoah ha-gid [the foundation of the world is in the power of the Phallus]. It is not impossible to find in the expression yesod ha-ʿibbur here an allusion to this.
In Wolfson’s esoteric interpretation, Crescas’s text wondrously jumps to life. Although God himself is thoroughly transcendent—that is, he transcends the ten divine Sefirot—he is also immanent by virtue of those very Sefirot, which constitute the divine emanative process and which are known in scripture as “His Glory.” It is furthermore suggested that “the element of impregnation”—that is, the principle of emanation—refers to the divine phallus. The universe is permeated with the divine eros.
Shortly after Wolfson’s Crescas’ Critique of Aristotle was published, he received a communication from the young Gershom Scholem in Jerusalem, who suggested that Crescas was alluding to the Kabbalistic secret of “the body of the pregnant” (Ecclesiastes 11:5). The universe is pregnant with the divine. Being is born out of the conjunction between the masculine element of impregnation and the feminine body of the pregnant.
Crescas’s discussion of yesod ha-ʿibbur, as explicated by Wolfson, must be counted as one of the great Kabbalistic texts concerning the relationship between God’s transcendence and immanence. It combines physics (infinite space, three dimensions), metaphysics (divine transcendence), and erotic mysticism (the element of impregnation), and it explains the ontic role of the divine Sefirot. Scholars of Jewish thought were profoundly impressed by Wolfson’s physico-Kabbalistic interpretation, elaborated on it, and cited relevant supporting texts from the Kabbalistic literature. In addition to Scholem, other scholars who accepted Wolfson’s analysis and expanded on it include Simcha Bunim Urbach, Shalom Rosenberg, Moshe Idel, and yours truly.
However, not all scholars were so impressed. In a 1933 review of Wolfson’s book, Julius Guttman, then of Berlin, rejected his Kabbalistic interpretation of the passage as “far-fetched” (die weit hergeholte Erklärung). The passage, he pronounced bluntly, has nothing at all to do with Kabbalah. The reading ʿibbur, he continued, makes no sense and is evidently incorrect. Guttman suggested reading ʿobi (meaning coarseness, thickness) instead of ʿibbur. The passage, according to him, would have the following sense:
Though God is holy and separated by a threefold holiness, alluding thereby to His separation from three worlds [the world of four elements, the celestial spheres, and the separate intellects], still the whole earth, which is the coarsest of the [four] elements, is full of His Glory.
Although God is transcendent, his glory is present even in the coarsest of the four elements: the element of earth. “Earth,” in Crescas’s text, does not refer to the world or to the universe, but to the element of earth, which is coarser than the elements of water, air, or fire and much coarser than the celestial element of ether. In Guttmann’s interpretation, Crescas’s passage refers wholly to physics and has no hint of Kabbalah.
Wolfson makes light of Guttmann’s criticism:
Guttmann suggests to change yesod ha-ʿibbur to yesod ha-ʿobi. Now, if a term meaning “crass,” “coarse,” or “gross” would satisfy him in this context, why not change it to yesod ha-ʿikkur [“the element of turbidity”] or ha-yesod he-ʿakhur [“the turbid element”] or still better yesod he-ʿafar [“the element of earth”] …But the very fact that as soon as a conjectural emendation is suggested there appear at once three equally good terms to which the extant reading can be changed shows how hazardous and arbitrary such emendations are. But I have shown, and I believe quite convincingly…that the entire passage…reflects Cabbalistic discussions of the Sefirot and this naturally leads one to expect that the term yesod ha-ʿibbur must likewise contain an allusion to Cabbalistic terminology. To change it to any other term would destroy that allusion and would thus strip the term of the special significance which we feel it must have here in this particular Cabbalistic context.
Guttmann’s criticism was generally ignored by scholars, who were thoroughly captivated by Wolfson’s stunning discussion of yesod ha-ʿibbur. I believe many of them thought that Guttmann was a conservative scholar (ein Jecke) who was unable to imagine that Kabbalistic allusions could be found in a philosophic book. Wolfson’s interpretation, they may also have felt, was just too good to forgo. This changed abruptly in 1990 when Rabbi Shlomo Fisher published his edition of Crescas’s Or Adonai, and he surprisingly read yesod he-ʿakhur (“the turbid element”) instead of yesod ha-ʿibbur (“the element of impregnation”). Fisher understood the text precisely in the way Guttmann had understood it, although he did not adopt his reading yesod ha-ʿobi but preferred Wolfson’s suggestion, yesod he-ʿakhur. Fisher’s status as a distinguished Talmudist compelled scholars to rethink Crescas’s passage. Éric Smilévitch, in his 2010 French translation, follows Guttmann and Fisher, translating it “sa Gloire emplit pourtant toute la terre, bien qu’elle soit le plus vil des éléments.” Roslyn Weiss, in her new English translation, follows Guttmann, Fisher, and Smilévitch, translating it “His glory fills all the earth, which is the most turbid of the elements.” These scholars are now followed by Daniel Levin in his recent edition of Or Adonai.
A few years ago I reexamined very carefully the 13 extant manuscripts of the Light, and I found to my chagrin that indeed the textual evidence confirms the reading yesod he-ʿakhur. Guttmann, Fisher, and their followers were right. In point of fact, yesod he-ʿakhur is not a textual emendation, but the superior reading attested in the best manuscripts.
Alas, what about Wolfson’s brilliant Kabbalistic discussion of yesod ha-ʿibbur? Do we have to toss it into the trash bin? No, not at all! It remains a remarkable text illustrating the glorious erotic action of the divine Sefirot in the created universe. However, the credit for this Kabbalistic teaching can no longer be given to Crescas, but it must be given to Harry Austryn Wolfson. What he lost as a historian he regains as an original religious thinker.
In his Crescas’ Critique of Aristotle, Harry Austryn Wolfson analyzes in detail Rabbi Hasdai Crescas’s critique of Aristotelian physics. However, Wolfson had originally been drawn to Crescas not because of his contribution to the history of natural science, but because of his proto-Pragmatic philosophy, which is “old wine that is even now bursting new bottles.” He presented Crescas as a forerunner of American Pragmatism, a philosopher whose theory of time was worth comparing with that of Bergson, and an original and profound mystic.
 (Cambridge, MA: Harvard University Press, 1929).
 Ibid., 114-127.
 Leo W. Schwartz, Wolfson of Harvard (Philadelphia: Jewish Publication Society, 1978), 5-15.
 Ibid., 20-30.
 Ibid., 33-36.
 Jewish Quarterly Review 2 (1912): 297-337. See my “Hebraism and Western Philosophy in H.A. Wolfson’s Theory of History,” Immanuel 14 (1982): 77-85.
 “Maimonides and Halevi,” 306, 336. Note that it is implied here that poetry (“synagogal hymns”) is more Hebraic than halakhah (“talmudic Law”).
 Ibid., 335-336. See Crescas, Light of the Lord, trans. Roslyn Weiss (Oxford: Oxford University Press, 2018), 221; Or Adonai, ed. Shlomo Fisher (Jerusalem: Ramot, 1990), 246. In quotations, Weiss’ translation may sometimes be modified.
 “Maimonides and Halevi,” 336. See Crescas, Light, 222; Or Adonai, 247.
 “Maimonides and Halevi,” loc. cit.
 Schwartz, 39-59. Wolfson completed the manuscript of Crescas’ Critique of Aristotle in 1917. Owing to World War I and difficulties securing funding, the book was not published until 1929.
 See my Hebrew Rabbi Hasdai Crescas (Jerusalem: Zalman Shazar Center, 2010), 106, 111-113, 164. Texts supportive of Pragmatism are found without difficulty in the Light, e.g., “the practical part [ha-ḥeleq ha-maʿasi] is the final cause of the intellectual [ha-sikhli]” (Light II.6.1, 212; Or Adonai, 235).
 James, A Pluralistic Universe (New York: Longmans, Green, 1909), 223-274.
 Jewish Quarterly Review 10 (1919): 17.
 Crescas’ Critique of Arisotle, 97.
 Light, 89; Or Adonai, 85. Weiss translates, “the measure of the continuousness of motion or rest between two instants.”
 Cf. Aristotle, Physics, IV.11.219a-220a.
 Crescas’ Critique of Aristotle, 288-289. See pp. 93-98; 651-658, n. 23. See also “Note on Crescas’ Definition of Time.” Cf. my “The Term Hitdabbekut in Crescas’ Definition of Time,” Jewish Quarterly Review 71 (1981): 44-47.
 Crescas’ Critique of Aristotle, 97.
 “Note on Crescas’ Definition of Time,” 10.
 Crescas’ Critique of Aristotle, 657, n. 23; cf. 96-98.
 Bergson, Creative Evolution, trans. Arthur Mitchell (New York: Henry Holt, 1911), 46; L’Évolution créatrice (Paris: Alcan, 1907), 50. Crescas, Light, 90; Or Adonai, 85-86; Wolfson, Crescas’ Critique of Aristotle, 290-291.
 Creative Evolution, 46; L’Évolution créatrice, 49. Bergson’s statement that time is non-recurring (la même réalité concrète ne se répète jamais) is against both Newton and Nietzsche. On the parallelism of space and time in Crescas’ physics, see my Physics and Metaphysics in Hasdai Crescas(Amsterdam: Gieben, 1998), 4-8.
 See Jimena Canales, The Physicist and the Philosopher: Einstein, Bergson, and the Debate that Changed our Understanding of Time (Princeton: Princeton University Press, 2015).
 Crescas’ Critique of Aristotle, 201. Cf. Light, 77; Or Adonai, 69-70.
 Sefer ha-ʿIbbur, ed. S.J.C. Halberstam (Lyck: Mekize Nirdamim, 1874), 16.
 Sefer Abudarham (Venice: Giorgio de Cavalli, 1566), 113a.
 Crescas’ Critique of Aristotle, 459-460, n. 92.
 Wolfson, “Studies in Crescas,” Proceedings of the American Academy for Jewish Research 5 (1933 – 1934), 160.
 Urbach, ʿAmude ha-Maḥashabah ha-Yisraʾelit, vol. iii (Jerusalem: Jewish Agency, 1961), 107, n. 70.
 Rosenberg, “Notes on the Concept of Infinity in Medieval Jewish Philosophy” (Hebrew), MA thesis, The Hebrew University of Jerusalem, 1970, 78-80.
 Idel, “Explanations of the Secret of Impregnation in 13th-Century Catalonian Kabbalah” (in Hebrew), Daat 72 (2012): 1-45; “The Secret of Impregnation as Metempsychosis in Kabbalah,” in Aleida and Jan Assmann, eds., Verwandlungen: Archäologie der literarischen Kommunikation IX(Munich: Wilhelm Fink, 2006), 341-379, esp. 354, 374-376; “In a Whisper: On Transmission of Shiʿur Qomah and Kabbalistic Secrets in Jewish Mysticism,” Rivista di Storia et Letteratura Religiosa 47 (2011): 443-488, esp. 474.
 Harvey, “Holiness: A Command to Imitatio Dei,” Tradition 16, no. 3 (1977): 10; “Kabbalistic Elements in Rabbi Hasdai Crescas’ Light of the Lord” (in Hebrew), Jerusalem Studies in Jewish Thought 2 (1983): 92-95.
 Guttmann, Bűcherbesprechungen, Zeitschrift der Deutschen Morgenlāndischen Gesellschaft 11 (1933): 228.
 “Studies in Crescas,” 159.
 I cannot deny that I myself may once have been biased toward Wolfson and against Guttmann. I was a student of Arthur Hyman, a leading disciple of Wolfson’s, and considered Wolfson the paragon of scholarship. At the same time, influenced by Leo Strauss’ Philosophie und Gesetz (1935), I saw Guttmann as someone who is wary of outside-the-box ideas.
 Or Adonai, 70.
 Crescas, Lumière de l’Éternel, trans. Éric Smilévitch (Paris: Hermann, 2010), 396.
 Light, 77.
 Ed. Daniel Levin (Bat-Yam: Shinmem, 2020), 57.
 See my “A Dubious Kabbalistic Secret in Crescas’ Light of the Lord” (in Hebrew), in Avriel Bar-Levav, ed., Moshe Idel Jubilee Volume (forthcoming). It should be added that the adjective ʿakhur is used in medieval Hebrew to describe the element of earth. See, e.g., the anonymous early 13th-century Aristotelian book, Ruaḥ Ḥen (“The Graceful Spirit”), ed. Ofer Elior (Jerusalem: Yad Ben-Zvi, 2017), 251: “Concerning these four elements…fire is the purest and thinnest of all, and earth the thickest and most turbid [he-ʿakhur].”