Period of Aristotle

Change of substance (transformations, in particular of the elements earth, water, air and fire into each other). This is mainly a chemical change in the modern terms. 

Change of quality or alteration. For example, a hot object becomes a cold object. 

On the motion of celestial bodies like the Sun and Moon, he postulated that they are composed of ether (quintessence) and hence have tendency to move in a circle, because circles are perfect. Explanation of how an arrow keeps on moving when released from bow is explained in the following manner. When an arrow moves, it creates a vacuum. As the nature abhors vacuum, the air rushes to fill up the vacuum left behind and in the process applies force on the tail of the arrow. Aristotle believed that an arrow would not be able to move in vacuum. We know today that it is wrong in fact arrow will move more easily in vacuum, because of the absence of the drag force of the air. 

About rains, Aristotle explained in the following matter. Water on earth is warmed by the Sun, changes into the air and rises up, because the air has a natural tendency to move up. Then the air cools down, changes into the water and becomes heavier, and finally falls down as the rain again. This description is weak from the point of view of modem science, but is reasonable considering the state of science during the days of Aristotle. 

The pseudo-Aristotelian Mechanical Problems is considered to be the first surviving ancient Greek text on mechanics (Coxhead 2012). The prefix pseudo is used because it is not certain if the book was actually authored by Aristotle or embodies 

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