11. It is the same with certainty as with other objects of human knowledge. The fact is presented to us in all its magnitude, and with all clearness; but we do not penetrate to its innermost nature. Our understanding is as well provided with means to acquire knowledge of phenomena in the spiritual as in the material order, and it is sufficiently perspicacious to detect, delineate, and classify the laws to which they are subject; but when it would ascend to the cognition of the very essence of things, or would investigate the principles of the science which makes its boast, it feels its strength fail, and the ground whereon it stands, tremble and sink beneath its feet. Happily, man possesses certainty independently of philosophical systems, not limited to phenomena of the soul, but extending as far as is needed in order to direct his conduct, both with regard to himself and to external objects. Before inquiring if there is certainty, all men were certain that they thought, willed, felt, that they had a body whose motions were governed by the will, and that there existed an assemblage of various bodies, called the universe. Since inquiries with regard to certainty were first instituted, it has remained the same with all men, even with those who disputed it; not one of whom could ever go farther than Pyrrho, and succeed in casting off human nature. 12. We cannot determine to what extent the force of mind of some philosophers, engaged in combatting nature, may have succeeded in creating doubt on many points, but certain it is: first, that no one ever went so far as to doubt the internal phenomena whose presence he felt inwardly; second, that if indeed any one ever did persuade himself that no external object corresponded to these phenomena, this must have been so strange an exception as to merit, in the history of science, and in the eyes of sound philosophy, no more weight than the illusions of a maniac. If Berkely went so far as to deny the existence of bodies, thus making the sophisms of reason triumph over the instincts of nature, he is alone, and in opposition to all mankind, and richly merits to have this saying applied to him: "Insanity is insanity still, no matter how sublime it may be."