What is their poetry about?

From the text:

In poetry, they must be allowed to excel all other mortals; wherein the justness of their similes, and the minuteness as well as exactness of their descriptions, are indeed inimitable. Their verses abound very much in both of these, and usually contain either some exalted notions of friendship and benevolence or the praises of those who were victors in races and other bodily exercises.