the principle from which one sets out, and upon the manner in which one looks at things. Reason does not give this principle; it is no more master of the end which it goes to attain, than the straight line drawn upon the ground is master of the point toward which it tends. This end and this point are determined beforehand, by the position of the reasoner or by geometry. Reason exists alike in the three great human modifications, although its principal seat is in the soul, according to Plato.[515] There is a physical reason acting in the instinct, a moral reason acting in the soul, and an intellectual reason acting in the mind. When a hungry dog brings to his master a piece of game without touching it, he obeys an instinctive reason which makes him sacrifice the pleasure of gratifying his appetite, to the pain of receiving the blow of a stick. When a man dies at his post instead of abandoning it, he follows a moral reason which makes him prefer the glory of dying to the shame of living. When a philosopher admits the immortality of the soul, he listens to an intellectual reason which shows him the impossibility of its annihilation. All this, nevertheless, takes place only so far as the dog, the man, and the philosopher admit the real principles; for if they admitted false principles, their reasons, although equally well deduced, would conduct them to opposed results; and the piece of game would be eaten, the post would be abandoned, and the immortality of the soul would be denied.