Some adopt the principle that reason is man's only guide,--that reason alone is judge of what is true and good, and that to reason every thing must be submitted, and received or rejected, done or left undone, as reason may decide. This sounds very plausible to many, and there is a sense in which it may be true; but there is a sense in which it is fearfully false; and the youth that adopts it, and acts upon it, will be likely to land himself in utter doubt, both with regard to religion and morals. There are numbers of cases in which reason is no guide at all,--in which instinct, natural affection, and consciousness are our only guides. You can never prove by what is generally called reason alone, that man is not a machine, governed entirely by forces over which he has no control. You cannot therefore prove by what certain philosophers call reason, that any man is worthy of reward or punishment, of praise or blame, of gratitude or of resentment; or that there is any such thing in men as virtue or vice, according to the ordinary sense of the words. The ablest logicians on earth, when they take reason alone as their guide, come to the conclusion that there is no such thing as liberty or moral responsibility, in the ordinary acceptation of the terms, but that all is fixed, that all is fate, from eternity to eternity. They accordingly come to the further conclusion, that there is no free, voluntary Ruler of the universe,--that there is no Almighty Judge and Rewarder,--that there is neither reward nor punishment, properly speaking, either in this world or in the world to come. They become atheists.