"At the beginning God created matter in
the form of a hard, massy, impermeable,
moveable particles (...) And that primary
particles are such a hard bodies that they
never wear and never crumble (...)"
- Isaac Newton

Leonardo da Vinci (1452-1518) should be a well-known person, because of his art. Not only an artist but he was also the first one trying to understand structure of matter (like friction, water's conversion into ice etc.) in experimental way. He built many of the first machines for scientific research. We still wonder about his uncommonly discerning mind, broad thinking and sphere of skilful activity.

Galileusz Galileo Galilei, (1564-1642) was the scientist who laid the foundation for an experimental research of nature. Among other things he did, he also researched an atom. Thanks to him, ideas of Democritus reappeared. Galileo was of the opinions that matter and light consisted of point particles. He imagined that world consisted of countless atoms separated by quantitatively infinite vacuum. In his work - "Dialogo sopra i due massimi sistemi del mondo" he included (among the other problems) his opinion on study of atom. As some historians of science say, Galileo's vision of atom described the particle as an indivisible formation but without a shape and also without dimensions at all. So from the mathematical point of view it was an abstract. That was at variance with the theorem of Democritus that basic particles had different shapes. Galileo was the first scientist, who used experimental methods in the process of researching the world. Unfortunately experiments couldn't help him enough in forming opinions of world's microstructure. Everything he achieved in study of atom he did thanks to mental experiments and logical exercises.

Evangelist Torricelli, (1608-1647), was Galileo's prominent disciple. By analysing problems connected with pumping water and by making experiments in which he replaced water with mercury he has proved the existence of vacuum. Notice that it is the first time we say that somebody has PROVEN something!

Robert Boyle,Robert Boyle, (1627-1691), was another great scientist of the 17th century. He performed many experiments. He did the research on the effect of air resistance, its pressure and on changes of its volume, while changing its pressure. He discovered the law describing dependence between these two quantities (Boyle's law). You surely remember it from school (it should be somewhere in the beginning of your notes from lessons about thermodynamics). This law was experimentally discovered by Boyle but formulated later by Marriotte. The experiments with pressure were quiding later scientists, who were researching air structure. The experiments proved that air is composed of separate, moving atoms, which stay, in quite a distance from each other. Thanks to such structure, air can change its volume considerably. Pressure, which Boyle researched, is caused by the movement of particles, which collide with other things influencing them with some force. When air's volume is smaller, there are more collisions in each square centimetre of surface (what Bernoullie's researches showed later). This interdependence Boyle discovered in an experimental way. Boyle had also many other successes in researching world's microstructure. He refuted the publicly accepted statement that mercury is in every (also living) body (he grew bean in a dish filled only with water). He was looking for matter's basic components. That's why he was trying to brake apart different substances. When he couldn't divided something any more he called it "simple body". All other things were to be composed of those simple bodies. Aristotle's four elements were replaced by Boyle with his simple bodies. Nobody knew the number of them. That complicated the vision of the world, so most of the scientists of this period was against Boyle sugestion. The other Boyle's theorem was the existence of elusive, fire substance - "fire matter". This substance was supposed to evaporate with fire during burning. Its existence was to be shown also as rust and debris.

Antonie von Leeuwenhoek, Dutch scientist, (1632-1723), in 1670 created the first microscope. Although by today's standarts it is laughably primitive, think what a turning - point for science that was. It gave the possibility to change the whole viewpoint for many processes of world's existence. It could've change the scales of estimation and foremost the scale of investigation. What interests us here is the study of atom, and microscopes are the fundamental instruments there. As you probably noticed we have said "could've" not "did". That is because for almost 200 years after being discovered microscope have been used mostly as a kind of toy (only for rich people of course) showing "nice pictures".

Isaac Newton, the greatest of the 17th century, lived from 1643 to 1727. Among many other achievements in physics, mathematics and astronomy, he was also researching world's microstructure. Like the earliest scientists his opinion was, 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 interaction between different bodies as 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, amaterial medium was to penetrate whole space, making the contact between bodies possible. But ether also had to be composed of particles and that made logical contradictions.

    The 17th century completely changed scientists' opinions on laws ruling the universe and on microstructure of matter. That was the time of many astronomical discoveries in astronomy and mathematical achievements . But the development in physics was the fastest. It used new mathematics. Newton's discoveries created new ideas which, with no important changes, remained till the beginning of the 20th century. After one and a half thousand years Democritus's concept of atom reappeared . The existence of vacuum was proven (Torricelli). A new study of atom developed. But still it wasn't known whether atom existed or not; Boyle's experiment was only an indirect proof of it. The achievements of the 17th century atomists were mostly based on logic.. Scientists didn't have proper equipment for reassert. It was the time of constructing first experimental instruments like the first microscope (Leeuwenhoek).