"Greek mathematical thought does, indeed deal first and last with different kinds of numbers. Were it otherwise, how would it be possible to come to terms with the limitlessness of the material with which arithmetic is confronted? Therefore... theoretical arithmetic... attempts to comprehend all possible groupings of monads in general under arrangements which are determinate, i.e., which possess unambiguous characteristics and which may, in turn, be reduced to their own ultimate elements... Now the most comprehensive eide, those which come closest to the rank of ' and are therefore termed "the very first"... are the odd and the even. ...each of these halves nevertheless comprising an unlimited multitude of numbers. But each of these... is now in turn gathered "into one"... by means of certain unambiguous characteristics..."