40 Columella says (lib. 3, cap. 8) that in Egypt and Africa the bearing of twins was frequent and even customary; gemini partus familiares, ac pæne solennes sunt. If this was true, there is a physical difference both in countries and ages, for travellers make no such remarks of these countries at present; on the contrary, we are apt to suppose the northern nations more fertile. As those two countries were provinces of the Roman Empire, it is difficult, though not altogether absurd, to suppose that such a man as Columella might be mistaken with regard to them.

41 This too is a good reason why the smallpox does not depopulate countries so much as may at first sight be imagined. Where there is room for more people they will always arise, even without the assistance of naturalisation bills. It is remarked by Don Geronimo de Ustariz that the provinces of Spain which send most people to the Indies are most populous, which proceeds from their superior riches.

42 The same practice was common in Rome, but Cicero seems not to think this evidence so certain as the testimony of free citizens. (Pro Cælio.)