to be determinate, or to have a form, in that case it becomes one of the very things which call for explanation. In other words, the question instantly arises, Whence this determinate matter? And suppose that the answer again is, It arises out of determinate matter, this determinate matter again requires explanation, and so on for ever, so that no approach at all is made to an explanation if, in explaining the origin of determinate or apparent matter, we are always referred to an antecedent determinate matter; and therefore, if this explanation of the origin of material things is to be held good for anything, we must ultimately be thrown in upon a matter which is altogether formless and indeterminate. This is the conception which Anaximander appears to have reached, and which he expressed by the term ἄπειρον, the conception of a materia prima, a matter which, having no form or determination in itself, is capable of receiving all forms or determinations. That which is open to, and recipient of, all forms or qualities must in itself be invested with no form or quality, otherwise it would be foreclosed against the reception of other qualities.
19. Such is the ἄπειρον of Anaximander, in which we seem to find the germ of the distinction between matter and form, a distinction which afterwards became conspicuous in several schools of philosophy, and which, when construed into logic, became convertible with genus and difference; genus was matter,
