Isaac Newton, the greatest of the 17th century, lived from 1643 to 1727. Among many other achievements in physics, mathematics and astronomy, he also making researches of world's microstructure. Like the earliest scientists he also believed that matter consisted of atoms. Their existence was to be proven only by intellectual experiments. He maintained that light was also composed of some kind of atoms. Solar rays were to be streams of particles. He perceived an interaction between different bodies as the interaction between atoms of these bodies. He paid much attention to the problem of action at a distance. For a long time he was considering the existence of ether, which as an ideal, a material medium was to penetrate the whole space, making the contact between bodies possible. But ether also had to be composed of particles and that made logical contradictions.