In this respect Stoicism betrays its descent from the encyclopaedic lectures of the earlier Sophists, particularly Hippias. While professedly subordinating every other study to the art of virtuous living, its expositors seem to have either put a very wide interpretation on virtue, or else to have raised its foundation to a most unnecessary height. They protested against Aristotle’s glorification of knowledge as the supreme end, and declared its exclusive pursuit to be merely a more refined form of self-indulgence;[20] but, being Greeks, they shared the speculative passion with him, and seized on any pretext that enabled them to gratify it. And this inquisitiveness was apparently much stronger in Asiatic Hellas, whence the Stoics were almost entirely recruited, than in the old country, where centuries of intellectual activity had issued in a scepticism from which their fresher minds revolted.[21] It is mentioned by Zeller as a proof of exhaustion and comparative indifference to such enquiries, that the Stoics should have fallen back on the Heracleitean philosophy for their physics.[22] But all the ideas respecting the constitution of Nature that were then possible had already been put forward. The Greek capacity for discovery was perhaps greater in the third century than at any former time; but from the very progress of science it was necessarily confined to specialists, such as Aristarchus of Samos or Archimedes. And if the Stoics made no original contributions to physical science, they at least accepted what seemed at that time to be its established results; here, as in other respects, offering a marked contrast to the Epicurean school. If a Cleanthes assailed the heliocentric hypothesis of Aristarchus on religious grounds, he was treading in the footsteps of Aristotle. It is far more important that he or his successors should have taught the true theory of the earth’s shape, of the moon’s phases, of eclipses, and of the relative size and distance of the heavenly bodies.[23] On this last subject, indeed, one of the later Stoics, Posidonius, arrived at or accepted conclusions which, although falling far short of the reality, approximated to it in a very remarkable manner, when we consider what imperfect means of measurement the Greek astronomers had at their disposition.[24]