The ultimate "principle" he designated, like Plato, as the absolute One, but it was not to be regarded as an existing entity, since all entities can only be the result of development. When, however, with the Pythagoreans, he reckoned the "One" in the series of "good" things, he probably conceived it only in its opposition to the "Many", and wished to indicate that it was from the "One" and not from the "Many", that the good and perfect is to be derived. Nevertheless, Speusippus seems to have attributed vital activity to the primordial Unity, as inseparably belonging to it, probably in order to explain how it could grow, by a process of self-development, into the good, spirit, etc.; for spirit also he distinguished from the one, as well as from the good; and the good from pleasure and pain. Less worthy of notice is the attempt by Speusippus to find a more suitable expression for the material "principle", the indefinite duality of Plato; and his Pythagorizing mode of treating the doctrine of numbers which we can see in the extracts of his treatise on the Pythagorean numbers.