"Aristotle died in the year 322 B.C. By A.D. 100 the predominant centre of intellectual development had shifted to Alexandria. ...By the later Alexandrian period... salvation had become paramount and men doubted whether, without... Divine Revelation, their perplexities about Nature could be resolved... The principle... that men... must offer cogent arguments in support of their statements had been abandoned. In the intermediate period we find... men as Archimedes, Hipparchus, and Euclid retained the rational scientific ideals of the classical philosophers, and carried their analyses to new levels of refinement and sophistication. But alongside... we find the beginnings of gnosticism—the claim that one can more certainly achieve... truth by way of asceticism, purification and mystical practices. Between these extremes lie two major schools of philosophers, whose teachings could be interpreted in alternative ways—either as rational systems of natural philosophy or with an eye to their religious significance. These two aspects were already present in the case of Epicurus for whom was as much a weapon against the terrors of contemporary religion as it was a detailed theory of Nature. And a similar double purpose is apparent in the world-system of the Stoics."