In 1911, Russian-born theorist and pioneer of abstract art Vassily Kandinsky published Concerning the Spiritual in Art, which ranks among the most significant documents in 20th-century art. Kandinsky writes, “All means [in painting] are sacred when they are dictated by inner necessity. All means are reprehensible when they do not spring from the fountain of inner necessity.” In this treatise, he calls for a spiritual revolution in painting that permits artists to abstractly express their own inner lives through form and color, and to value spirituality over naturalistic or materialistic representations.