If this proves to be the case we may then consider Speusippus and Xenocrates, as to whose spec - ulation we are perhaps better informed, to see if their metaphysics may reasonably be supposed to have evolved from Plato's agrapha dogmata.    From Wordnik.com.  [Dictionary of the History of Ideas] Reference

It represents in its main lines the thought not only of Speusippus and Xenocrates but also, as far as we can discern, that of Plato in the agrapha dogmata or “unwritten doctrines” (Ross, pp. 142-53; Merlan, pp. 11-33; Krämer, pp. 1-2; Gaiser with frags.).    From Wordnik.com.  [Dictionary of the History of Ideas] Reference