The science of the sixth century was mainly concerned, then, with those parts of the world that are “aloft” (τὰ μετέωρα), and these include, along with the heavenly bodies, such things as clouds, rainbows, and lightning. That is how the heavenly bodies came sometimes to be explained as ignited clouds, an idea which seems astonishing to us. But we must bear in mind that science inevitably and rightly began with the most obvious hypothesis, and that it was only the thorough working out of this that could show its inadequacy. It is just because the Greeks were the first people to take the geocentric hypothesis seriously that they were able to go beyond it. Of course the pioneers of Greek thought had no clear idea of the nature of scientific hypothesis, and supposed themselves to be dealing with ultimate reality. That was inevitable before the rise of Logic. At the same time, a sure instinct guided them to the right method, and we can see how it was the effort to “save appearances”[46] that really operated from the first. It is, therefore, to those men that we owe the conception of an exact science which should ultimately take in the whole world as its object. They fancied—absurdly enough, no doubt—that they could work out this science at once. We sometimes make the same mistake nowadays; and it can no more rob the Greeks of the honour of having been the first to see the true, though perhaps unattainable, end of all science than it can rob our own scientific men of the honour of having brought that end nearer than it was. It is still knowledge of the kind foreseen and attempted by the Greeks that they are in search of. Footnote 46: This phrase originated in the school of Plato. The method of research in use there was for the leader to “propound” (προτείνειν, προβάλλεσθαι) it as a “problem” (πρόβλημα) to find the simplest “hypothesis” (τίνων ὑποτεθέντων) on which it is possible to account for and do justice to all the observed facts (σῴζειν τὰ φαινόμενα). It was in its French form, _sauver les apparences_, that the phrase acquired the meaning it usually has now. [Sidenote: Schools of philosophy.] XIV. Theophrastos, the first writer to treat the history of Greek philosophy in a systematic way,[47] represented the early cosmologists as standing to one another in the relation of master and scholar, and as members of regular societies. This has been regarded by many modern writers as an anachronism, and some have even denied the existence of “schools” of philosophy altogether. Such a reaction against the older view was quite justified in so far as it was directed against arbitrary classifications like the “Ionic” and “Italian” schools, which are derived through Laertios Diogenes from the Alexandrian writers of “Successions.” But the express statements of Theophrastos are not to be so lightly set aside. As this point is of great importance, it will be necessary to elucidate it still further before we enter upon our story.