This is an analysis of the interrelation between the abstract artist Mondrian's paintings, and his theories on art and life as expressed in his public writings and largely unpublished letters. Mondrian's art was not based on reasoning or calculation (on the contrary, intuition was central to his concept of the artistic process), but he always felt a strong urge to position his art in a wider cultural and philosophical context. Central to his thought was the theosophical notion of evolution, which required the destruction of the old to make room for the new - in life, in society, and in art. The book concentrates on the paintings, Mondrian's major achievement, examining the influences that shaped his art: fauvism and cubism circa 1910, and the work of Bart van der Leck, De Stijl and the Parisian art world during the 1920s. Mondrian appears not as an isolated figure, but as an artist who took a keen interest in the world around him, a veritable avant-garde painter who saw his role as creator of a new, modern culture.