(Aristotle, Metaphysics, Book V, Chapter VIII) most modern definitions tell us that the first term is unvarying, of all that exists, preserved despite all the changes. Note that we speak of matter, which the ancients called substance. Discuss the concept of law is not easy but can be applied to the reality of things through logical connections which experience shows us. We know that the law is a necessary foundation to the nations of the earth, for not having them soon succumb to anarchy and chaos. Forward some laws: The law of contradiction: two statements can not be true or false at the same time when we talk about a subject. Example: Aristotle is seated and is running. The law of conservation of energy: the energy to move from one form to another, it disappears, or created, when a material passes from one state to another of its energy change corresponds closely to the increase or to lower energy of the bodies to and interact with the system. The biogenetic law: according to which each agency in the process of individual development, and special features repeating some of the ways that their ancestors were taken in the course of its evolution.

Kepler's Laws 1) each planet moves around the sun, describing an ellipse with the sun at one focus. 2) the radius vector from the sun to the planets sweeps out equal areas in equal times. 3) the squares of the periods of the planets are proportional to the cubes of their mean distances from the sun. Explanation of Kepler's laws 1) the planets move with uniform motion around the sun, but move more quickly when closer to it, and slower when farther away. July 2007 Jose Orlando Melo Naranjo 2) join two positions of the planet in its orbit with the focus that represents the position of the sun, the line joining the sun to any part of the planetary orbits is called the radius vector. 3) to compare the size of the orbits of the planets with the time spent on a ride around the sun, or his term, the square of the period is proportional to the cube of the average distance to the sun.

I believe that given clearer meaning of such concepts is much easier to understand the theory of Anaximander. This thinker like Thales of Miletus was a practical man. Thanks to these qualities is remembered by history. I pass over some of the theories of Anaximander to deal with his disciple Anaximenes. The interesting thing as physicists, mathematicians, historians, philosophers, writers, sociologists, biologists and chemists, is the discovery of the truths we get and modify according to errors of the standard, leaving only the dogmas is like grasp.