The concept of causality, though constantly invoked to substantiate the scientific character of ancient thought, and especially Pre-Socratic thought, has been treated in a peripheral or fragmentary manner¹. Scholars and historians of the scientific and philosophical thought of this period, including Wheelwright, Sabursky, Guthrie and others² emphasize the paramount historical and scientific importance of causality. Some contend that in the sixth century B.C., scientific endeavour and success was due to the use and formulation of four principles ("traits"): (1) the tracing back of many phenomena to a few causes, (2) the reduction of quality to quantity, (3) the use of considerations of symmetry and (4) the employment of mechanical models ([16], p. 16). Indeed, as the results of my study of the available material (ascribed to the Pre-Socratics) show, causality is a very crucial and indispensable concept which enables us not only to understand and estimate the contribution of these pioneers of science, but also to be better able to see its development in a historical perspective and therefore to have the general epopteia of human thought. My purpose, then, is to identify the various causal patterns utilized by the Pre-Socratics in their endeavour to explain natural events. The variety and modes of function of these patterns are commented on and, whenever material is available, compared with conceptions of causality. However, it must be pointed out that since the material refers to the initial stage of science, the treatment will mainly be based on conventional, and often (to some extent) unelaborated patterns of causality. Obviously, no use is made of later theoretical distinctions [3, 6, 13], subtle conceptual elucidations or disputes and controversies [4, 5, 9, 15, 18] about the philosophical status and the function of causality.