“The Bahir’s idea of the sefiroth appears in Isaac’s writings in a fully crystallized form. In his commentary on the Yesirah 4:3, the verse 1 Chronicles 29:11 is used for the first time as a biblical reference for the names and the sequence of the seven lower sefiroth, especially the first five among them: “Yours, Lord, are the greatness (gedullah), might (geburah), splendor (tif’ereth), triumph (nesah), and majesty (hod)—yes all (kol) that is in heaven and on earth; to You, Lord, belong kingship (mamlakhah) and preeminence above all.”
From here come the designations not yet used in the Bahir, of gedullah for hesed, tif’ereth for ‘emeth, and hod. Isaac himself for the most part uses the names hesed and pahad (as in the Bahir) instead of gedullah and geburah. The name tif’ereth, however, is already familiar to him.
Whereas the word kol, occurring in the aforementioned verse, already served in the Bahir as an epithet designating the “Righteous,” Isaac uses for this sefirah the noun “Righteous” and the epithet “Foundation of the world.” For the last sefirah, on the other hand, he employs almost exclusively an epithet still not familiar to the Bahir, although it is undoubtedly alluded to there.
This epithet is ‘atarah, a synonym for kether, which designates the lowest of the ten “crowns.” Like the Bahir, he names the first three sefiroth kether or mahshabah, hokhmah and binah.
In his commentary on Yesirah, Isaac mentions many of these sefiroth in the framework of fixed schemata, but this does not always enable us to comprehend the sequence of the sefiroth within them. What is strange is that in point of fact the structure of the sefiroth beyond the supreme three only interests him in detail when it is a question of prayer mysticism, or the interpretation of certain ritual commandments. They have their importance as stages of the contemplative ascent or of the eschatological elevation of the soul, after death, to even higher spheres.
But never are any coherent thoughts presented concerning their function and structure. This is particularly the case for the potencies of tif’ereth, yesod and ‘atarah, which play an especially important role in the evolution of the doctrine of the sefiroth. In contrast to this lack of interest in detail, one discerns in Isaac a more pronounced interest in the totality of the spiritual potencies expressed in language and, in a more general manner, in spiritual entities.
Having said that, the terminological differences between concepts like sefiroth, middoth, letters (of the alphabet) and hawwayoth (literally: essences) are by no means always clear, and their interpretation is often fraught with difficulties.
However, these difficulties are closely related to what is truly new in Isaac’s Kabbalah. Indeed, from the historical point of view their interest lies in the combination of the world of ideas of the Bahir and the entirely new elements that erupt, inspired by gnostic ideas, into the oldest form of the Kabbalah as represented by the Bahir.
This combination reflects speculative interests whose origin is no longer essentially determined by Gnosticism but rather by Neoplatonism and a language mysticism generated by the latter. Isaac is visibly struggling with new thoughts for which he is as yet unable to find clear and definitive expression. The awkwardness of his new terminology militates against the supposition that this lack of clarity, which often makes it so difficult to penetrate his meaning, is intentional.
His new terminology seems to be derived from philosophy, although we cannot identify its philosophical sources in the Hebrew tradition. The special importance of Isaac’s commentary on the Yesirah lies in the attempt to read into the old texts the new, speculative thoughts of a contemplative mystic. But we are no less surprised by the boldness with which he presents far-reaching ideas in his other cosmological fragments and in his remarks concerning the mystical theory of sacrifice. The particular manner in which Isaac applies his ideas to the task of man, to the connection between the terrestrial and the celestial worlds, and to eschatological matters merits closer consideration.
The path of the mystic, described by Isaac at the beginning of his commentary on the Yesirah, is (as Isaac of Acre already recognized in his paraphrase of several of these passages in his own commentary) that of systematically uncovering the divine—by means of reflective contemplation and within the innermost depths of such contemplation. Isaac postulates three stages in the mystery of the deity and its unfolding in creation and revelation.”
Gershom Scholem, Origins of the Kabbalah, pp. 263-5.