The arguments that have been directed against the theory of natural moral perceptions are of two kinds, the first, which I have already noticed, being designed to show that all our moral judgments may be resolved into considerations of utility; the second resting upon the diversity of these judgments in different nations and stages of civilisation, which, it is said, is altogether inexplicable upon the supposition of a moral faculty. As these variations form the great stumbling-block in the way of the doctrine I am maintaining, and as they constitute a very important part of the history of morals, I shall make no apology for noticing them in some detail. In the first place, there are many cases in which diversities of moral judgment arise from causes that are not moral, but purely intellectual. Thus, for example, when theologians pronounced loans at interest contrary to the law of nature and plainly extortionate, this error obviously arose from a false notion of the uses of money. They believed that it was a sterile thing, and that he who has restored what he borrowed, has cancelled all the benefit he received from the transaction. At the time when the first Christian moralists treated the subject, special circumstances had rendered the rate of interest extremely high, and consequently extremely oppressive to the poor, and this fact, no doubt, strengthened the prejudice; but the root of the condemnation of usury was simply an error in political economy. When men came to understand that money is a productive thing, and that the sum lent enables the borrower to create sources of wealth that will continue when the loan has been returned, they perceived that there was no natural injustice in exacting payment for this advantage, and usury either ceased to be assailed, or was assailed only upon the ground of positive commands. Thus again the question of the criminality of abortion has been considerably affected by physiological speculations as to the time when the fœtus in the womb acquires the nature, and therefore the rights, of a separate being. The general opinion among the ancients seems to have been that it was but a part of the mother, and that she had the same right to destroy it as to cauterise a tumour upon her body. Plato and Aristotle both admitted the practice. The Roman law contained no enactment against voluntary abortion till the time of Ulpian. The Stoics thought that the infant received its soul when respiration began. The Justinian code fixed its animation at forty days after conception. In modern legislations it is treated as a distinct being from the moment of conception.(112) It is obvious that the solution of such questions, though affecting our moral judgments, must be sought entirely outside the range of moral feelings.