Were Isaac Newton and Montesquieu alive at the same time?
Yes. Isaac Newton and Montesquieu were alive at the same time for 38 years, from 1689 to 1727.
Isaac Newton was 46 when Montesquieu was born.
Montesquieu was 38 when Isaac Newton died, aged 84.
Isaac Newton
English mathematician and physicist
Born 25 December 1642 (Julian calendar) · died 20 March 1727 (Julian calendar), aged 84