"So the same light of the mind which enabled them to see (albeit without knowing why) that virtue is preferable to pleasure, the good preferable to the useful, also enabled them to grasp true ideas in philosophy and mathematics, although they were not yet able fully to master such sciences"
— Descartes, René (1596-1650)
(Rule 4, p. 17-20)
See Opuscula posthuma, physica et mathematica (Amsterdam: P. and J. Blaeu, 1701).
Not published in Descartes' lifetime. Dutch translation in 1684; published in Latin in 1701.