Again, from memory (sorry if mistaken): Leibniz and Newton were in disagreement on the nature of the fundamental constituent of our universe. Leibniz thought it monads; Newton thought it Force.

I suppose they were both right (except for the aiua quality Leibniz seemed to think monads possessed, to borrow a concept from Orson Scott Card), though it was not at all obvious at the time - and to some degree still isn't.