 According to Aristotle, all three of Plato, Speusippus, and Xenocrates constructed their worlds operating with two principles (archai): the One and something opposed to it. The latter appears under different names, and it looks as if the different names go with different ones among the three: ‘the Indefinite Dyad’ or ‘the large and (the) small’ seem to be the expressions favored by Plato, ‘plurality’ seems to be associated with Speusippus, and ‘the unequal’ with Xenocrates. And for Plato, the One was identified with the Good. These philosophers employed these two principles, according to Aristotle, to generate derivative entities (substances, beings) of other types: Forms, numbers, and so on. This generation was laid out as if it were a process in time, but the generation-story was to be understood instead as one understands a mathematical construction: the construction takes place in time, but what is constructed is an eternal structure. And in this eternal structure the principles were not temporally first, but first in relation to the dependence on them of the things constructed.