The Essence of Sufism was written by Japanese thinker and Islamic philosopher Toshihiko Izutsu. The work centers on the concept of waḥdat al-wujūd (Oneness of Being), a doctrine with a significant place in Islamic thought, and examines its historical development, theoretical framework, and linguistic foundation through a philosophical analysis. The book is grounded in the idea that the conceptual structure of Sufism must be evaluated not only through surface-level symbols but also through the deeper ontological heritage underlying them.

Subject

This book focuses on the Sufi trends that have shaped the metaphysical dimensions of Islamic thought, analyzing the doctrine of waḥdat al-wujūd (Oneness of Being) at both a philosophical and conceptual level. Rather than being understood merely as a belief principle or mystical intuition, waḥdat al-wujūd is presented as a full-fledged theory of being (ontology). The text investigates how this doctrine articulates a profound understanding of existence that goes beyond symbolic expressions and traditional Sufi terminology.

The author approaches waḥdat al-wujūd as a comprehensive framework, analyzing key concepts within this system—such as truth (al-Ḥaqq), the cosmos (ʿālam), the human being, and the relationship with God—particularly in terms of ontological dualities like transcendence and immanence. This analysis is carried out not only in terms of content but also from linguistic and semantic perspectives. The origins of these concepts, their layered meanings in Arabic, and their usage in classical Sufi texts are examined in a systematic manner.

In addition, the position of the human being in Sufi thought is treated as a major theme. Within this worldview, the human being is defined as the vicegerent (khalīfa) of God on Earth and as a being who contains the essence of existence. In this context, the concept of the insān al-kāmil (Perfect Human) is discussed from both ontological and epistemological angles.

The author argues that the doctrine of waḥdat al-wujūd is not merely a mystical inner experience but a comprehensive view of existence. Consequently, the book seeks to explain how this theory functions as a system of Islamic cosmology. The relationship between God's absolute existence and the multiplicity (kathrah) of created beings is analyzed through classical Sufi terms such as tajallī (divine manifestation), ʿayn (essence), ẓill (shadow), and inzāl (emanation/descent).

Themes Covered

Waḥdat al-Wujūd (Oneness of Being):

The central theme of the book, the concept of waḥdat al-wujūd, is subjected to both linguistic and philosophical deconstruction. The depth of the metaphysical understanding of being in Sufism is critically examined.

Hierarchy of Being:

The gradations of existence, the relationship between God, the cosmos, and the human being, as well as the process of creation, are presented in relation to the conceptual hierarchy within the Sufi metaphysical system.

Theoretical and Symbolic Language:

Sufi language is addressed not merely as a poetic expression, but as a medium that contains deep structural meanings. The metaphysical content behind terms and symbols is analyzed through a semantic and linguistic approach.

Philosophical–Sufi Interaction:

The book explores the interaction between Sufi thought and Islamic philosophy, particularly how the metaphysical system of Ibn al-ʿArabī corresponds with, diverges from, or transforms philosophical concepts.