Sextus Empiricus Pyrrhoniae Hypotyposes 3.20.162

[162] but if each partakes of its own monad, we must posit a new monad for each of those monads, and others again for the former, and so on ad infinitum. If then, in order to apprehend that there are certain self-sub-sistent monads by participation in which each existing thing is one, it is necessary to apprehend an infinite infinity of intelligible monads, and to apprehend an infinite infinity of intelligible monads is a thing impossible, then it is impossible to show that there are certain intelligible monads and that each existing thing is one through becoming one by participation in its own monad.