Book III concerns the "System of the World, that is, the sun, the planets and their moons, and certain comets. In it Newton attempted to show that his law of universal gravitation sufficed to explain in detail the phenomena of celestial mechanics. Since the mathematical structure presented in Book I was insufficient to treat a universe containing more than two bodies, Newton had to resort here to approximations of various sorts. Here, too, he showed himself a consummate master of mathematics and of ingenious guessing. (Clifford Truesdell 1968).
I am puzzled of how rendering in French the sentence in bold.
Google translate gives:
Là aussi, il se montra un maître accompli en mathématiques et en devinettes ingénieuses.
DeepL gives a similar interpretation.
But I am wondering if devinette renders correctly the sense of guessing in this context.