Yet the legislation of Augustus in favour of marriage, and the universal lamentation of the later Roman writers over the extinction of the old Roman stock, are no more than a presumption that the population was decreasing, not a proof of its actual smallness, while the prevalence of war and infanticide, so often used to prove the same point, tend really to do the opposite. They are for the time positive encouragements to marriage, for people will not hesitate to bring children into the world, if they are either free to kill off the superfluous or certain to find sad vacancies ready for them.[217] In the former case, as we noticed, parental feeling will often interfere with the infanticide, and save rather too many than too few.[218] Wars, on the other hand, may injure the quality of the population by removing the most stalwart and even the most intelligent men; but there is as much food as before, there is more room, and there are therefore more marriages, till all the gaps are filled, even to overflowing.[219] Livy need not have wondered that in the Volscian wars the more were killed the more seemed to come on. The like is true of plague and famine; epidemics, like the small-pox, have never permanently lessened the population, though they have increased the mortality of the infected countries.[220] To take only one instance (from Süssmilch)—a third of the people in Prussia and Lithuania were destroyed by the plague in 1710, and in 1711 the number of marriages was very nearly double the average.[221] Emigration in like manner may drain off the best blood of a nation, but cannot reduce its numbers for any length of time, unless the nation is learning a new standard of comfort. Greece and Rome were not less populous because they were great colonizers.[222] The known existence of a number of very active checks to population, instead of proving that the population was absolutely small, might more naturally, other things being equal, prove it to have been absolutely large. It might be argued that, if the population had not been great, fewer and less potent checks would have done the work.[223] But other things were not equal. We know that the gratuitous distribution of foreign corn had ruined Roman husbandry.[224] We know that even the labour of the slaves who had supplanted the free labourers of Italy had not been sufficiently (or sufficiently well) directed to agriculture. Moreover, the increase by marriage in the number of slaves did not even balance the decrease in the number of the free men; else why should the Romans need to import fresh cargoes of slaves every year from all parts of the world?[225]