A recurrent and striking feature of reflection on wholes and parts, both in ancient and modern times, is the attempt to draw a distinction between what might be described as higher-grade and lower-grade wholes. Perhaps the earliest example of such a distinction is that standing at the source of the present work, namely, Plato's distinction in Theaetetus between a complex which is different from all its elements and a complex which is identical to them. A more familiar ancient example is found in Aristotle's distinction between substances and heaps. In early modem times, Leibniz distinguishes similarly between monads and monadic aggregates.¹ In the 19th and early 20th centuries, two notions in particular developed into central representatives of this perennial attempt to explicate a higher-grade type of whole: The notion of an organic whole, and the notion of a Gestalt.² The latter two are fairly described as the main traditional modem notions of higher-grade wholes.