the doctrine that all of reality can be derived from a single principle, "the One".

Neoplatonism began with Ammonius Saccas and his student Plotinus ( - 271) and stretched to the sixth century. After Plotinus there were three distinct periods in the history of Neoplatonism: the work of his student Porphyry (third to early fourth century); that of Iamblichus (third to fourth