We must call astronomy to our aid if we would reach the truth. In the same way, ordinary or psychological thinking may show us the apparent movements of thought--but it is powerless to decipher the real figures described in that mightier than planetary scheme. Metaphysic alone can teach us to read aright the intellectual skies. Psychology regards the universe of thought from the Ptolemaic point of view, making man, as this system made the earth, the centre of the whole: metaphysic regards it from the Copernican point of view, making God, as this scheme makes the sun, the regulating principle of all. The difference is as great between "the science of the human mind" and metaphysic, as it is between the Ptolemaic and the Copernican astronomy, and it is very much of the same kind. But the opposition between psychology and metaphysic, which we would at present confine ourselves to the consideration of, is this:--the psychological blindness consists in supposing that the analysis so often referred to is practicable, and has been made out: the metaphysical insight consists in seeing that the analysis is null and impracticable. The superiority of metaphysic, then, does not consist in doing, or in attempting more than psychology. It consists in seeing that psychology proposes to execute, the impossible, (a thing which psychology does not herself see, but persists in attempting;) and it consists, moreover, in refraining from this audacious attempt, and in adopting a humbler, a less adventurous, and a more circumspect method. Metaphysic (viewed in its ideal character) aims at nothing but what it can fully overtake. It is quite a mistake to imagine that this science proposes to carry a man beyond the length of his tether. The psychologist, indeed, launches the mind into imaginary spheres; but metaphysic binds it down to the fact, and there sternly bids it to abide. _That_ is the profession of the metaphysican, considered in his beau-ideal. That, too, is the practice (making allowance for the infirmities incident to humanity, and which prevent the ideal from ever being perfectly realised)--the practice of all the true astronomers of thought, from Plato down to Schelling and Hegel. If these philosophers accomplish more than the psychologist, it is only because they attempt much less.