A serious answer to this question would go something as follows. Many of the Ancient Greeks believed that the best poetry and drama reveals to us universal truths. These are truths about the human situation: about how human beings will react under certain circumstances; about how they relate to one another; about the sort of things they face by virtue of the fact that they are human; and so on. And we can learn these from a study of the classics. So, for example, it is a "truth" seen in many Greek works that human beings are subject to forces beyond their control (which, in Greek theatre, was often represented by the Gods who would toy with humans as they saw fit). These forces predetermine what will happen to us and, no matter how hard we try to avoid it, we will eventually meet this predetermined fate. A more detailed answer than this would require a greater knowledge of the classics than I possess (unfortunately- the side effect of a deprived education in a typical British comprehensive school).