This work introduces a semiotic and phenomenological understanding of the four elements: Earth, air, fire and water, as they appear in description and depiction. The book develops a theory of the imaginary in human thought, and examines the occurrence of the elements, not in their role as trivial contents of the imaginary, but rather as aspects of its constitutive background - as material dimensions giving rise to direct and dynamic cognitive structure. The elements thus evoke universally evaluated sensations, and provide simple schematic conceptual primitives, in contrast with complex higher-order metaphoric structures which may rely on them. The elements are here understood as a mental palette in perception, as well as in aesthetic and philosophical expression. The validity of this view is demonstrated by analyzing literary works by Soren Kierkegard, Thorkild Bjornvig, Simon Grotrian and Arne Johnsson, and painting by J.M.W. Turner and Edward Hopper. The analysis is based on an empirical application of catastrophe theory to works of art, and it proposes new semiotic techniques for the interpretation of art and imagination in general.