The progressive development of moral and intellectual man has scarcely occupied their [scientists] attention; nor have they noted how the faculties o… - Adolphe Quetelet

What becomes of human free will and agency? ...it seems to me to involve one of the most admirable laws of conservation in nature—a law which presents a new proof of the wisdom of the Creator... It is necessary, then, to admit that free-will exercises itself within indefinite limits, if one wishes not to incur the reproach of denying it altogether. But, with all the follies which have passed through the head of man, with all the perverse inclinations which have desolated society, what would have become of our race during so many past ages? All these scourges have passed by, and neither man nor his faculties have undergone sensible alterations, as far at least as our observations can determine. This is because the same finger which has fixed limits to the sea, has set similar bounds to the passions of men—because the same voice has said to both, "Hitherto shalt thou come, and no farther!"

I would suggest... the idea of a work which should have for its object the analytic examination of the development of our intellectual faculties for each age. Now, I have aimed to present, in the work here reproduced, only an essay, only a particular example, of such an analysis, "which tends to show that the maximum of energy of the passions occurs about the age of twenty-five." The minimum is not then determined; and even when it shall be, by a sufficient number of observations, one will no more be able to apply it to any given individual in particular, than one could make use of a table of mortality to determine the period of his decease.

The more advanced the sciences have become, the more they have tended to enter the domain of mathematics, which is a sort of center towards which they converge. We can judge of the perfection to which a science has come by the facility, more or less great, with which it may be approached by calculation.