Ein Sof (Hebrew: אין סוף, “without end” or “infinite”) is a concept in Kabbalistic Jewish mysticism referring to the aspect of God that precedes and transcends all manifestation, definition, and limitation. It is generally distinguished from the sefirot, the ten emanations through which the infinite is understood to interact with and become knowable within creation. Because Ein Sof is held by most Kabbalistic sources to be fundamentally beyond description, the term is used both as a name for the divine in its most concealed aspect and, in some usages, as a label for the entire process by which the infinite contracts and emanates outward; this distinction, along with the broader question of how Ein Sof relates to the personal God of rabbinic tradition, is contested. See ein-sof-personal-god-viewpoint-debate.

The concept of Ein Sof developed within medieval Kabbalah, most notably in the Provençal and Spanish circles associated with the Sefer ha-Bahir and later systematized in the Zohar and the school of Isaac the Blind and his successors. Ein Sof is generally treated as prior to and unrepresented within the sefirot themselves, with the sefirot understood as the vessels or channels through which Ein Sof's light (or emanation) becomes structured and ultimately accessible to created beings. The relationship between Ein Sof and the first sefirah, Keter, is a recurring point of technical disagreement among Kabbalistic schools, with some treating Keter as continuous with Ein Sof and others treating it as the first genuine point of differentiation. For historical development of the concept across different Kabbalistic schools, see ein-sof-history.

A central interpretive question concerns how Ein Sof, as infinite and unbounded, can give rise to a finite and bounded creation. The Lurianic Kabbalah associated with Isaac Luria addresses this through the doctrine of tzimtzum, in which Ein Sof is understood to contract or withdraw to create a conceptual space within which finite creation can exist. The proper interpretation of tzimtzum - whether as a literal withdrawal, a metaphor for divine concealment, or a paradox not meant to be resolved discursively - is a matter of ongoing debate among later Kabbalists and scholars of Jewish mysticism. See ein-sof-tzimtzum-interpretation-debate. The concept also plays a role within the broader doctrine of the Four Worlds, in which Ein Sof's emanation is understood to pass through successive levels of increasing differentiation and materiality; see Four Worlds (Kabbalah).

• Impersonal Ground-of-Being Viewpoint - Holds that Ein Sof represents an impersonal, undifferentiated ground of existence prior to any attributes, will, or personality, with the personal, willing, commanding God of biblical and rabbinic tradition emerging only at the level of the sefirot or further down the chain of emanation.
• Continuous Personal God Viewpoint - Holds that Ein Sof and the personal God of Jewish tradition are not separate entities but a single divine reality considered under different aspects, with Ein Sof denoting that same God's infinite and unknowable dimension rather than a distinct, more fundamental layer.
• Literalist Tzimtzum Viewpoint - Holds that the Lurianic doctrine of tzimtzum describes an actual, if mysterious, act of divine self-limitation or withdrawal, prior to and as a precondition for creation, rather than a purely figurative or pedagogical device.
• Non-Literal Tzimtzum Viewpoint - Holds that tzimtzum should be understood metaphorically or psychologically, as describing the limits of human perception of the divine rather than any actual change, withdrawal, or limitation occurring within God, since an infinite being cannot coherently be said to literally contract.
• Philosophical Rationalist Viewpoint - Holds that the Kabbalistic elaboration of Ein Sof and the sefirot represents an unwarranted multiplication of divine attributes or quasi-independent entities, in tension with a strict philosophical monotheism and the negative theology associated with thinkers such as Maimonides.
• Academic Historical-Critical Viewpoint - Holds that Ein Sof and related Kabbalistic doctrines are best studied as historically and culturally situated developments within medieval and early modern Jewish thought, shaped by identifiable textual lineages and external philosophical influences, rather than as direct or uniquely authoritative accounts of the nature of God.

• The reception and partial adoption of Lurianic concepts including Ein Sof and tzimtzum within Sabbatean and later antinomian movements has been a documented source of dispute within Jewish religious and scholarly communities over the proper boundaries and consequences of Kabbalistic doctrine. See ein-sof-sabbatean-reception-controversy.

• History of Ein Sof
• Debate: Literal vs. Figurative Interpretation of Tzimtzum
• Viewpoint Debate: Impersonal Ground-of-Being vs. Continuous Personal God
• Controversy: Sabbatean Reception of Lurianic Doctrine
• Four Worlds (Kabbalah)
• Sefirot
• Kabbalah
• Jewish Mysticism
• Tzimtzum

• Gershom Scholem, *Major Trends in Jewish Mysticism* (New York: Schocken Books, 1941).
• Gershom Scholem, *Kabbalah* (New York: Quadrangle/New York Times Book Co., 1974).
• Moshe Idel, *Kabbalah: New Perspectives* (New Haven: Yale University Press, 1988).
• Isaiah Tishby, *The Wisdom of the Zohar: An Anthology of Texts*, trans. David Goldstein (Oxford: Oxford University Press, 1989).
• Lawrence Fine, *Physician of the Soul, Healer of the Cosmos: Isaac Luria and His Kabbalistic Fellowship* (Stanford: Stanford University Press, 2003).