Social Philosophy, therefore, ought on every ground to be preceded by Natural Philosophy in the ordinary sense of the word; that is to say by the study of inorganic and organic nature. It is reserved for our own century to take in the whole scope of science; but the commencement of these preparatory studies dates from the first astronomical discoveries of antiquity. Natural Philosophy was completed by the modern science of Biology, of which the ancients possessed nothing but a few statical principles. The dependence of biological conditions upon astronomical is very certain. But these two sciences differ too much from each other and are too indirectly connected to give us an adequate conception of Natural Philosophy as a whole. It would be pushing the principle of condensation too far to reduce it to these two terms. One connecting link was supplied by the science of Chemistry which arose in the Middle Ages. The natural succession of Astronomy, Chemistry, and Biology leading gradually up to the final science, Sociology, made it possible to conceive more or less imperfectly of an intellectual synthesis. But the interposition of Chemistry was not enough: because, though its relation to Biology was intimate, it was too remote from Astronomy. For want of understanding the mode in which astronomical conditions really affected us, the arbitrary and chimerical fancies of astrology were employed, though of course quite valueless except for this temporary purpose. In the seventeenth century, however, the science of Physics specially so called, was founded; and a satisfactory arrangement of scientific conceptions began to be formed. Physics included a series of inorganic researches, the more general branch of which bordered on Astronomy, the more special on Chemistry. To complete our view of the scientific hierarchy we have now only to go back to its origin, Mathematics; a class of speculations so simple and so general, that they passed at once and without effort into the Positive stage. Without Mathematics, Astronomy was impossible: and they will always continue to be the starting-point of Positive education for the individual as they have been for the race. Even under the most absolute theological influence they stimulate the Positive spirit to a certain degree of systematic growth. From them it extends step by step to the subjects from which at first it had been most rigidly excluded.