The paper deals with Aristotleś conception of nature and wspecially his physics. In the first part the fundamental ideas concerning Aristotleś philosophy of nature and his definition of nature as four causes are introduced. The second part discusses the concept of motion as the change from potentiality to actuality. In the third part Aristotleś understanding the notions of time and place - basic notions for description of motion - is explained; classification of the enforced motion is also given there. In the next part we look closely at the notion of the mover - one of four causes of nature - and Aristotleś law of force - quantitative relation between the mover and weight and velocity of the moved body. This part further deals with the motion in material environment. It describes the role of air in the motion where direct contact between the mover and the moved body is absent (antiperistasis). A brief sketch of the criticism of Aristotleś physics is given in the final part.