merely primitive; it is, again, constant and universal, since we encounter it at each moment of each life, and in the most complicated as well as in the simplest.  Let us accordingly ascertain whether it is not the thread with which all our mental cloth is woven, and whether its spontaneous unfolding, and the knotting of mesh after mesh, is not finally to produce the entire network of our thought and passion. — Condillac (1715-1780)provides us here with an incomparable clarity and precision with the answers to all our questions, which, however the revival of theological prejudice and German metaphysics was to bring into discredit in the beginning of the nineteenth century, but which fresh observation, the establishment of mental pathology, and dissection have now (in 1875) brought back, justified and completed.[23] Locke had already stated that our ideas all originate in outward or inward experience.  Condillac shows further that the actual elements of perception, memory, idea, imagination, judgment, reasoning, knowledge are sensations, properly so called, or revived sensations; our loftiest ideas are derived from no other material, for they can be reduced to signs which are themselves sensations of a certain kind.  Sensations accordingly form the substance of human or of animal intelligence; but the former infinitely surpasses the latter in this, that, through the creation of signs, it succeeds in isolating, abstracting and noting fragments of sensations, that is to say, in forming, combining and employing general conceptions. — This being granted, we are able to verify all our ideas, for, through reflection, we can revive and reconstruct the ideas we had formed without any reflection.  No abstract definitions exist at the outset; abstraction is ulterior and derivative; foremost in each science must be placed examples, experiences, evident facts; from these we derive our general idea.  In the same way we derive from several general ideas of the same degree another general idea, and so on successively, step by step, always proceeding according to the natural order of things, by constant analysis, using expressive signs, as with mathematicians in passing from calculation by the fingers to calculation by numerals, and from this to calculation by letters, and who, calling upon the eyes to aid Reason, depict the inward analogy of quantities by the outward analogy of symbols.  In this way science becomes complete by means of a properly organized language.[24] — Through this reversal of the usual method we summarily dispose of disputes about words, escape the illusions of human speech, simplify study, remodel education, enhance discoveries, subject every assertion to control, and bring all truths within reach of all understandings.

V. The analytical method.

The analytical method. — Its principle. — The conditions requisite to make it productive. — These conditions wanting or inadequate in the 18th century. — The truth and survival of the principle.