CHAPTER IX PROTYLE: WHAT IS IT? The notion of a primordial form of matter meets us at every stage of cosmogonical speculation. It is the outcome of an instinctive persuasion that, if we could only 'lift the painted veil' of phenomena, the real business of the universe would be found to be proceeding in the background, 'without haste or rest,' on a settled plan everywhere the same; that uniformity is fundamental, diversity only incidental; and that the transformations of the one simplified substance might be represented by a single formula, the discovery of which would place in our hands the master-key to the locked secrets of the universe. Among untutored thinkers some familiar kind of matter, idealized and generalized, commonly stood for the typical world-stuff. Water was the first favourite. Thales, the 'wise man' of Miletus, procured his cosmos by precipitation from an aqueous solution, and many savage tribes have devised analogous expedients. Anaximenes regarded air as the universal solvent; Heracleitus replaced it with fire, and set on foot a scheme of what is now often designated 'elemental evolution.' From the perpetual 'flux of things' he conceived that the four substances selected by Empedocles as the bases of nature were not exempt, and a fragment of his scheme survived in Francis Bacon's admission of the mutual convertibility of air and water. In the main, however, the author of the 'Novum Organum' adhered to the Paracelsian doctrine of an elemental triad,[52] although he regarded the association of salt as a fundamental 'principle' with sulphur and mercury as inept and unnecessary.[53] These twilight fancies faded in the growing light of chemical science; yet the mental need that they had temporarily appeased survived, and had somehow to be satisfied. An 'Ur-Stoff' was still in demand, but the nineteenth century characteristically attempted to supply it by weight and measure. Dalton's combining equivalents afforded the warrant for Prout's hydrogen hypothesis. The problem to be faced was to find a unit-atom by the varied combinations of which all the rest of the chemical atoms might be formed. The condition indispensable to be fulfilled was that their weights should be exact multiples of that of the unit, and it came near to fulfilment by the hydrogen-atom or semi-atom. It was, nevertheless, a case in which approximate agreement was of no avail; the adverse decision of the balance finally became unmistakable; and Prout discreetly fell back, in 1831,[54] upon the expedient of deriving hydrogen itself from some body lower in the scale. His hypothesis, in short, dissolved into a conjecture. It had only emphasized the stipulation that the 'protyle' of the ancients must be such as would serve not only for the physical unification of the sum of things, but likewise as the substratum of all the chemical species.