Voltaire Quote

The system of Descartes... seemed to give a plausible reason for all those phenomena; and this reason seemed more just, as it is simple and intelligible to all capacities. But in philosophy, a student ought to doubt of the things he fancies he understands too easily, as much as of those he does not understand.

Letters Concerning the English Nation (C. Davis, 1741), p. 99, Letter XV, On Attraction