During the last two centuries a remarkable similarity between the philosophical system of Plotinus (205-270 A.D.) and those of various Hindu philosophers in various centuries, including some that lived prior to the Third Century A.D. has been discovered. This book addresses the possibility of any direct influence of Indian thought upon Plotinus and his teacher Ammonius Saccas (185-250 A.D.) or even upon their major source, Plato. Are Platonism and Plotinism, and the thought patterns in Western religion, literature, and art derived from them, to be considered as mere variations on themes found in ancient Hindu philosophy or are they pure evolutionary products of Greek philosophy?