Wassily Kandinsky (1866-1944) was one of the most influential painters of the twentieth century, and Concerning the Spiritual in Art is universally recognised as an essential document of modernist art theory. It lays out the tenets of painting as he saw them and makes the case for non-objective artistic forms. Brilliant as a philosophical treatise and as emphatic as an avant-grade tract, Concerning the Spiritual in Art provides the theoretical underpinnings to the Expressionist movement in art. While Michael Sadler's masterful translation has been available since its original publication in 1914, under the title Concerning the Spiritual in Art, unknown until now is the significant correspondence between the translator and the artist, who closely followed the progress of his book's transformation into English, and who offered numerous insights and explanations into its meaning. Housed in the archives of Tate, these and other unpublished documents are appended to Kandinsky's text to provide the first comprehensively annotated edition of this seminal work. Included in this volume, essential for any student of modernism, and certain to supersede any previous edition, are the letters between Kandinsky and Sadler, and prose poems by Kandinsky relating to the period in which the book was written. More than a revised edition, this publication constitutes a major event, as the first full account of a remarkable literary collaboration and a crucial intellectual adventure.