? ?? ? ??? ?? ?? ??? ? ??? ???, ??? ??? ??? ??? ??? ? ????.René Descartes's sketch of how Major and secondary rainbows are formed, Discours de la Méthode, 1637. Descartes' 1637 treatise, Discourse on Strategy (Discours de la Méthode), additional State-of-the-art this clarification. Recognizing that the dimensions of raindrops did not seem to hav