I took especially great pleasure in mathematics because of the certainty and the evidence of its arguments. - René Descartes

For since, with a little well-directed effort, one can change the movements of the brain in animals devoid of reason, it is clear that this can be done even more successfully in human beings, and that even those who have the weakest souls could acquire a very absolute command of all their passions, if one were to take the trouble to train them and guide them properly.

Il est bon de savoir quelque chose des moeurs de divers peuples, afin de juger des nôtres plus sainement, et que nous ne pensions pas que tout ce qui est contre nos modes soit ridicule et contre raison, ainsi qu'on coutume de faire ceux qui n'ont rien vu.

Those who reason most powerfully and are the most successful at ordering their thoughts so as to make them clear and intelligible will always be best able to persuade others of what they say, even if they speak in the thickest of dialects