He begins by observing (1) that _all living things_, of whatever kind, when furnished with their proper nourishment tend to increase in a geometrical ratio, whether (as wheat) by multiplying sixfold in one year, or (as sheep) by doubling their numbers in two years, tending to fill the earth, the one in fourteen, the other in seventy-six years. But (2) as a matter of fact they do not so increase, and the reason is either man’s want of will or man’s want of power to provide them their proper soil or pasture. The actual rate of increase is extremely slow, while the power of increase is prodigious. (3) Physically man is as the rest; and if we ask what is the factor of his geometrical increase, we can only tell it, as in the case of wheat and sheep, by experience. (4) In the case of other living beings, where there are most room and food there is greatest increase. These conditions are best fulfilled for man in the United States, where the distribution of wealth is better than in other equally fertile places, and the greater number share the advantages. The American census shows for the three decades between 1790 and 1820 a rate of increase that would double the numbers in 22⅓, 22½, and 23⁷⁄₁₂ years respectively, after we deduct as immigrants ten thousand on an average every year. A striking indirect confirmation of this view of the American increase was supplied to Malthus[130] by Joshua Milne, the author of the _Treatise on Annuities_. His calculations were founded on the new Swedish table of mortality. This table had been drawn up from the registers of the first five years of the century, years of unusual healthiness; and might therefore be presumed to represent the normal condition of a new and healthy country like the United States better than the old table drawn up from the years before sanitary reform and vaccination. Milne took the Swedish table as his guide, and one million of people as his unit of measurement; he calculated in what proportions the component individuals of the million must belong to childhood, youth, mature life, and old age, in order that by the principles of the Swedish table the million might double itself by natural increase in twenty-five years; and he arrived at a distribution so like that given by the American census, that he was bound to conclude the American rate of increase to be at the least very like one that doubles a population in twenty-five years. But the Swedish law of mortality could not be exactly true of the United States, which are healthier as a whole than Sweden even in Sweden’s best years.[131] The United States themselves are not the very healthiest and wealthiest and happiest country conceivable; and their increase is therefore not the fastest conceivable. If the observed fact of increase is the best proof of the capacity for increase, the observed presence of checks leads to an _a fortiori_ reasoning, whereby we infer the capacity for a greater increase than any actually observed.