Ax: 100 Every thing doth naturally persevere in yt state in wch it is unlesse it bee interrupted by some externall cause, hence... [a] body once moved will always keepe ye same celerity, quantity & determination of its motion.
Isaac NewtonBy such deductions the law of gravitation is rendered probable, that every particle attracts every other particle with a force which varies inversely as the square of the distance. The law thus suggested is assumed to be universally true.
Isaac Newton