It has seemed to me that the theory (calcul) of probabilities ought to serve as the basis for the study of all the sciences, and particularly of the … - Adolphe Quetelet

The words cited from my work, when viewed isolatedly, are far from expressing the idea which I wished to attach to them. The works of genius upon which our judgments bear are in general complex; for there is no work, constructed by genius, which does not suppose the exercise of various of its faculties. A skilful analysis could alone make out the part of each of them...

As laws and the principles of religion and morality are influencing causes, I have then not only the hope, but, what you have not, the positive conviction, that society may be ameliorated and reformed.

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.