By substantial truth we mean this—that in all the great systems of opinion which have had a deep hold on the human mind, over broad spaces and through long periods, there is something suited to man’s nature, and corresponding with the facts of the case. The mind of man was made for truth, and not for error. Error is transient: truth only is permanent. Men do not love error for its own sake, but for the sake of something with which it is connected. After a while, errors are eliminated, and the substance retained. The great, universal, abiding convictions of men must, therefore, contain truth. If it were not so, we might well despair; for, if the mind of the race could fall into unmixed error, the only remedy by which the heart can be cured, and the life redeemed from evil, would be taken away. But it is not so. God has made the mind for truth, as he has adapted the taste to its appropriate food. In the main, and in the long run, what men believe _is the truth_; and all catholic beliefs are valid beliefs. Opinions held by all men, everywhere and at all times, must be substantially true. But error certainly exists, and always has existed. If the human mind is made for truth, how does it fall into error? There never has been any important question upon which men have not taken two sides; and, where they take two sides, one side must be in error. Sometimes these two parties are equally balanced, and that for long periods. With which has the truth been? Is God always with the majority? If so, we must at once renounce our Unitarian belief for the Trinity, as an immense majority of votes are given in its favor. But, then, we must also renounce Protestantism; for Protestantism has only eighty or ninety millions against a hundred and forty millions who are Catholics. And, still further, we must renounce Christianity in favor of Heathenism; since all the different Christian sects and churches united make up but three hundred millions, while the Buddhists alone probably exceed that number. Moreover, truth is always in a minority at first,—usually in a minority of one; and, if men ought to wait until it has a majority on its side before they accept it, it never will have a majority on its side.