????? ? ??? ??? ?????? ??? ??? ? ???, ??? ????? ?? ?? ??? ???? ??? ???? ??? ??? ??? ??? ? ????.René Descartes's sketch of how Main and secondary rainbows are fashioned, Discours de la Méthode, 1637. Descartes' 1637 treatise, Discourse on Approach (Discours de la Méthode), further more Highly developed this explanation. Being aware of which the d