When Aristotle gazed at the stars, he pondered neither the infinity of the universe nor the minuteness of our earth. For him, the universe was surrounded by spheres centered around the earth. There was a sublunary world below the moon and a world above it of divine perfection, but the world above did not go on forever. The universe was vast but finite. It was complex but could be grasped. It was what you saw in the sky on clear nights. Aristotle found himself at home in the sublunary world encased in the stellar reality of godly perfection. As mortal human beings, we were at home on earth, where things are impermanent and imperfect. The earth is our place. It is also a place driven by purpose.
Aristotle provides us with a different picture of causation than that of modern science. We tend to think of a cause as what makes something happen, as when one billiard ball hits another and makes it move. Aristotle believes there are four distinct categories of causes: material, efficient, formal, and final. Let us examine them in the case of making a ceramic coffee cup. The cup has to be made of matter. Aristotle calls this the material cause and, in our case, it is clay. The efficient cause is what makes something happen—here, the pottery maker. The cup must have the attributes of a coffee cup; not just anything will pass. Aristotle calls this set of attributes its formal cause. When our pottery maker shapes the cup, he has this formal cause in mind. The cup is made for drinking coffee—its final cause. Our pottery maker would keep the final cause in mind in order to make it a usable coffee cup.