When I attempt to convince any one that certain conduct which he considers right is wrong, by showing him that it is opposed to the general welfare, my final appeal is to his conscience. And in the same manner, when I correct some of my own moral conceptions, it is my conscience which determines me to the proof of them, and my conscience which is the standard that determines my decision. Conscience is the principle underlying my moral convictions. But I do not possess, in conscience, a moral power which never errs; hence it behooves me to judge carefully. Body and mind both have their laws on which depend the welfare and happiness of society; the last results of science and human experience give us these laws. There are few things in regard to which there is so great unanimity as there is in regard to the right and good. In the fundamental questions, all the more highly civilized peoples are, for the most part, agreed. On the lowest planes of civilization, only the narrowest tribal association is taken into consideration in morals, but gradually, with the growth of experience, growth of the understanding, which permits the recognition, in a much higher degree, of the results of action and the power of sympathy, ever larger circles of human beings are regarded,--the tribe, the nation, the whole of mankind, all sentient beings. In this development of conscience and benevolence, there is nothing to cause moral uncertainty or contempt of conscience; for, in that case, the fact that there was once a time when human beings were not on the earth must be a reason for contempt of everything human. We call various different things good, of worth, others bad, evil; there must be something common to all these, on account of which we apply the common term to them. That which is thus common to them is their relation to a consciousness for which they are good or bad, and not to a merely perceiving consciousness, but to one that feels and wills. As true and false relate to the intellectual side of human nature, so do good and bad relate to the side of feeling and will. Such things are good as are the mediate or immediate cause of agreeable states of consciousness or of the prevention or removal of disagreeable states; and on the other hand, such things are bad as are the cause of pain or the hindrance of pleasure. We say of these things that they are agreeable or disagreeable. Or we may use, instead of "agreeable," the term "object of desire," and instead of "disagreeable," the term "object of aversion"; for all that is agreeable has an attractive influence upon the will, and all that is disagreeable or painful has a repellant one. Joy is that condition of consciousness which we seek to attain and preserve, whose existence we prefer to its non-existence; and pain is that state of consciousness which we seek to avoid and destroy, whose non-existence we prefer to its existence.