The Shema prayer is, among other things, the demand to understand. Prominent thinkers such as Saadia Gaon, Bahya ibn Paquda and the Rambam all made tremendous efforts to understand it, which were highly controversial. This controversy pushed aside the discussion of the uniqueness of God, which ended up in the field of the history of ideas. This book is an attempt to revive the metaphysical reading of the uniqueness of God, while addressing these controversies. It offers a explanation of Shema, which is loyal to the constitutive Jewish sources on the one hand and in dialogue with modern thought on the other.