This paper is a study of the artistic philosophy of J. W. G. (Jock) Macdonald (1897-1960). It examines the implications of his initial break with representational art and his development of an abstract imagery between 1934 and 1941 in the context of the ideological tradition from which he emerged and the immediate cultural situation in which he worked. His personal writings are discussed and the iconographic content of his work is analyzed in relation to the evolution of his abstract style.  The roots of Macdonald's vision are located in the Romantic tradition, which assumes that the laws of nature and of art are the same and which inspired his use of the organic analogy. Macdonald's concept of nature is discussed in relation to the influence of significant scientific discoveries. A close study of his oeuvre reveals that his pictorial vocabulary of archetypal forms corresponds to a tradition of morphological research in biology and that his treatment of pictorial space was informed by scientific theories and by speculation about the "fourth dimension." Macdonald found in Theosophy and Anthroposophy a means to reconcile his fascination with science with his innately mystical apprehension of nature. Contradictory as they may appear, science and occultism formed the matrix of his semi-abstract and abstract art by suggesting ways to visualize nature's hidden energies