So is it with Ratiocination; and as we should betake ourselves to Newton for physical, not for theological conclusions, and to Wellington for his military experience, not for statesmanship, so the maxim holds good generally, “Cuique in arte suâ credendum est:” or, to use the grand words of Aristotle, “We are bound to give heed to the undemonstrated sayings and opinions of the experienced and aged, not less than to demonstrations; because, from their having the eye of experience, they behold the principles of things.(30)” Instead of trusting logical science, we must trust persons, namely, those who by long acquaintance with their subject have a right to judge. And if we wish ourselves to share in their convictions and the grounds of them, we must follow their history, and learn as they have learned. We must take up their particular subject as they took it up, beginning at the beginning, give ourselves to it, depend on practice and experience more than on reasoning, and thus gain that mental insight into truth, whatever its subject-matter may be, which our masters have gained before us. By following this course, we may make ourselves of their number, and then we rightly lean upon ourselves; we follow our own moral or intellectual judgment, but not our skill in argumentation. This doctrine, stated in substance as above by the great philosopher of antiquity, is more fully expounded in a passage which he elsewhere quotes from Hesiod. “Best of all is he,” says that poet, “who is wise by his own wit; next best he who is wise by the wit of others; but whoso is neither able to see, nor willing to hear, he is a good-for-nothing fellow.” Judgment then in all concrete matter is the architectonic faculty; and what may be called the Illative Sense, or right judgment in ratiocination, is one branch of it. Chapter IX. The Illative Sense.