We both call in experience to the support of our opinions; but, in your case, the experience is based on vague uncertainties, whilst I, more circumsp… - Adolphe Quetelet

The great body of population dynamics, like those of the motion of the celestial bodies, can be solved—and what is most remarkable, there is a surprising analogy between the formulas employed in these calculations. I believe that I have achieved to some extent what I have long said about the possibility of founding a social mechanics on the model established by celestial mechanics—to formulate the motions of the social body in accordance with those of celestial bodies, and to find there again the same properties and laws of conservation.

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.

Judgments upon books are formed with even more haste and levity than judgments upon men. Writings are talked of without being known; and people take up an opinion for or against, in consequence of decisions which it would cost them some trouble to determine the source. These are evils which must be borne with patience, and the more so because they are common.