text: But reason is not satisfied by obvious facts; its higher and nobler function is to deal with hidden things. Hidden things need proof; proof cannot come without doctrines; therefore, doctrines are necessary. That which leads to a general agreement, and likewise to a perfect one, is an assured belief in certain facts; but if, lacking this assurance, all things are adrift in our minds, then doctrines are indispensable; for they give to our minds the means of unswerving decision. Furthermore, when we advise a man to regard his friends as highly as himself, to reflect that an enemy may become a friend, to stimulate love in the friend, and to check hatred in the enemy, we add: "This is just and honourable." Now the just and honourable element in our doctrines is embraced by reason; hence reason is necessary; for without it the doctrines cannot exist, either. But let us unite the two. For indeed branches are useless without their roots, and the roots themselves are strengthened by the growths which they have produced. Everyone can understand how useful the hands are; they obviously help us. But the heart, the source of the hands growth and power and motion, is hidden. And I can say the same thing about precepts: they are manifest, while the doctrines of wisdom are concealed. And as only the initiated know the more hallowed portion of the rites, so in philosophy the hidden truths are revealed only to those who are members and have been admitted to the sacred rites. But precepts and other such matters are familiar even to the uninitiated.