First, maybe Alexander was great because of his accomplishments. This is an extension of the idea that history is the record of the deeds of great men. Now, of course, that's ridiculous. For one thing, half of people are women. For another, and this is important, there are lots of historical events that no one can take responsibility for, like, for instance, the Black Plague. Still, Alexander was accomplished. I mean, he conquered a lot of territory.