The human mind does not examine itself until well developed; then, at the first glance, it sees in itself a connection of sensations, ideas, judgments, and affections of a thousand kinds, the whole interwoven in an inextricable manner. To increase the complication, it is not alone, but in intimate relation with its like, in mutual communication of sensations, ideas, and sentiments; and all in their turn in contact with, and under the influence of, dissimilar beings of amazing variety, the union of which forms the universe. Shall it begin by throwing it all down? Shall it reduce all to ashes, and hope to rise like the phenix from the pyre? Shall it arbitrarily invent a fact, a principle, and say: "I must have a resting-point, I will take this, and upon it I will found science!" Shall we, before examining, before analyzing, say: "all this is one; there is nothing if there be not absolute unity; in it I place myself, and all that I do not see from my point of view I reject?" No! what we have to do, is first to ascertain what is in our mind, and then to examine, classify it, and give to it its true value; not commence by mad and impotent efforts against nature, but to lend an attentive ear to her inspirations. There is no philosophy without a philosopher; no reason without a rational being; the existence of the subject is then a necessary supposition. No reason is possible if the contradiction of being and not-being be possible; all reason, then, supposes the principle of contradiction to be true. When we examine reason it is reason that examines; it needs rules, light; all examination, then, supposes this light, the evidence and the legitimacy of its criterion. Man does not make himself, he finds himself already made; it is not he who imposes the conditions of his being; he finds them already imposed. These conditions are the laws of his being, and why contend against them? "Besides factitious prejudices," says Schelling, "man has others _primordial_, placed in him not by education, but by _nature herself_, which in _all_ men hold the place of principles of cognition, and are a _shoal_ to the free-thinker." For my own part I do not seek to be more than _all_ men; if I cannot be a philosopher without ceasing to be a man, I renounce philosophy and adhere to humanity. BOOK SECOND. ON SENSATION. CHAPTER I. SENSATION IN ITSELF. 1. Sensation considered in itself is simply an internal affection; but it is almost always accompanied by a judgment. This judgment may be more or less explicit and more or less noticed by the subject of the sensation. Suppose I see two architectural ornaments at a proper distance, and I discover no difference between them. In this sensation there are two things to be considered.