Selection from Jonathan Lear, Aristotle: The Desire to Understand, (New York: Cambridge University Press, 2009), 247-248.
Man is an inquirer who is able to abstract from certain features of reality in order to consider other features in depth. . . . When a mathematician considers a triangle as a triangle, he abstracts from the fact that it is made of bronze and considers only the properties it has in virtue of its being a triangle. Aristotle saw that this process of abstraction could be continued: ultimately it would yield a very abstract inquiry into reality. "There is a science," he says, "which investigates being as being." The expression "being as being" may seem odd, but Aristotle's idea is that man is able to conduct an inquiry into the broad structure of reality. Rather than focussing solely on particular aspects of reality--say, the heavens or living organisms, as the sciences of astronomy and biology do--man can also abstract from all the particular properties which make things the things they are and consider them merely as existing things. That is, man can inquire into reality as such. The desire to understand propels a man on from the first explorations of his immediate environment, to a search for explanations of why the world is the way it is, to, finally, the realization that man can transcend the explanation of this or that phenomenon and begin to inquire into the broad structure of reality. Aristotle discovered that there could be an inquiry into reality as such: as he put it, there is a single science which studies being as being.