Every term corresponds to a period of twenty-five years, and a glance at the figures will show us that population is supposed to double every twenty-five years, while the means of subsistence merely increases by an equal amount during each of these periods. Thus the divergence between the two series grows with astonishing rapidity. In the table given above, containing only nine terms, the population figure has already grown to twenty-seven times the means of subsistence in a period of 225 years. Had the series been extended up to the hundredth term a numerical representation of the divergence would have required some ingenuity. The first progression may be taken as correct, representing as it does the biological law of generation. The terms “generation” and “multiplication” are not used as synonyms without some purpose. It is true that doubling supposes four persons to arrive at the marriageable age, and this means five or six births if we are to allow for the inevitable wastage from infant mortality. This figure appears somewhat high to those who live in a society where limitation of the birth-rate is fairly usual. But it is certain that among living beings in general, including humankind, who are least prolific, the number of births where no restraint of any kind exists is really much higher. Women have been known to give birth to twenty or even more children. And there are no signs of diminishing capacity among the sexes, for population is still growing. In taking two as his coefficient Malthus has certainly not overstepped the mark.[295] The period of twenty-five years as the interval between the two terms is more open to criticism.[296] The practice of reckoning three generations to a century implies that an interval of about thirty-three years must elapse between one generation and another. But these are unimportant details. It is immaterial whether we lengthen the interval between the two terms from twenty-five to thirty-three years, or reduce the ratio from 2 to 1½, or even to something between 1¼ and 1¹/₁₀. The movement will be a little slower, but it is enough that its geometrical character should be admitted, for however slow it moves at first it will grow by leaps and bounds until it surpasses all limits. These corrections fail to touch the real force of Malthus’s reasoning concerning the law of reproduction.