How far, if at all, it is often asked, should sexual intercourse be continued after fecundation has been clearly ascertained? This has not always been found an easy question to answer, for in the human couple many considerations combine to complicate the answer. Even the Catholic theologians have not been entirely in agreement on this point. Clement of Alexandria said that when the seed had been sown the field must be left till harvest. But it may be concluded that, as a rule, the Church was inclined to regard intercourse during pregnancy as at most a venial sin, provided there was no danger of abortion. Augustine, Gregory the Great, Aquinas, Dens, for instance, seem to be of this mind; for a few, indeed, it is no sin at all.[11] Among animals the rule is simple and uniform; as soon as the female is impregnated at the period of oestrus she absolutely rejects all advance of the male until, after birth and lactation are over, another period of oestrus occurs. Among savages the tendency is less uniform, and sexual abstinence, when it occurs during pregnancy, tends to become less a natural instinct than a ritual observance, or a custom now chiefly supported by superstitions. Among many primitive peoples abstinence during the whole of pregnancy is enjoined because it is believed that the semen would kill the foetus.[12] The Talmud is unfavorable to coitus during pregnancy, and the Koran prohibits it during the whole of the period, as well as during suckling. Among the Hindus, on the other hand, intercourse is continued up to the last fortnight of pregnancy, and it is even believed that the injected semen helps to nourish the embryo (W.D. Sutherland, "Ueber das Alltagsleben und die Volksmedizin unter den Bauern Britischostindiens," _Münchener Medizinische Wochenschrift_, Nos. 12 and 13, 1906). The great Indian physician Susruta, however, was opposed to coitus during pregnancy, and the Chinese are emphatically on the same side.