"From the mathematical point of view there are infinitely many... numbers... Thus the first task of "scientific" arithmetic—as contrasted with... "practical" knowledge...— consists in finding such arrangements and orders of the assemblages of monads as will completely comprehend their variety under well-defined properties, so that their unlimited multiplicity may at last be brought within bounds (cf. Nichomachus I, 2). ...When we recall how Plato (Theaetetus 147 C ff.) makes Theaetetus, speaking from a very advanced stage of scientific geometry and arithmetic, describe his procedure... What... appears to Plato so exemplary for Socrates' present inquiry concerning "knowledge", and indeed for every Socratic inquiry of this kind[?]. Theaetetus... divides "the whole realm of number"... into two domains: to one of these belong all those numbers which may arise from a number when it is multiplied by itself... to the other, all those which may arise from the multiplication of one number with another. The first number domain he calls "square," the second "promecic" or "heteromecic" (oblong), designations which recur in all later arithmetical presentations (cf. Diogenes Laertius III, 24). Thus two eide [kinds, forms, or species]... allow us to articulate and delimit a realm of numbers previously incomprehensible because unlimited, especially if we substitute the various eide of polygonal numbers for the one eidos of oblong numbers."