The influence of Pythagoreanism of one form or another on Platonists from Speusippus in the Old Academy to Numenius of Apamea in the later second century AD can be seen to be pervasive, though never forming more than one element in the mix, along with Aristotelianism and Stoicism. If Speusippus and Xenocrates of Chalcedon established the doctrinal parameters of later Pythagoreanism, it is to another, rather idiosyncratic, member of the Old Academy that must go the honor of contributing significantly to the later life-myth of Pythagoras, namely Heraclides of Pontus. Philo of Alexandria shows in every aspect of philosophy how pervasive Pythagorean influence had become in the emerging amalgam that is Middle Platonism. To see how this influence develops further, one may turn to the major figure in the Platonist tradition from the later part of the first century AD, Plutarch of Chaeronea.

Numenius of Apamea is a thinker whom we know only from the reports of later witnesses who were anything but dispassionate historians of philosophy. Pythagorean is the most common epithet for Numenius. From the first book On the Good, Eusebius transcribes an arresting simile, which may, as its position in the arrangement of des Places implies, have served as an exordium to the main argument. Numenius can be reconciled with Plato if his cosmogony is interpreted as the playful or symbolic exhibition of an evergreen paradox. Numenius may be an eccentric Platonist, but it would be more eccentric still to call him anything other than a Platonist. Numenius seems not to have anticipated the Later Platonic postulate of a First Cause higher than intellect and being, but his fusion of metaphysics and psychology shows that he, like Plotinus, regarded the deliverance of the soul from its worldly attachments and the purification of the mind from error as inseparable goals.