Sextus Empiricus: Selections from the Major Writings on Skepticism Man and God by Hallie, Sextus
I'm not even 1/2 way through, but a couple of interesting things have come up so far. First, it drives home the fact that scepticism did not begin with Descartes. For example, Sextus notes that men disagree about questions of theology and ethics, and argues that we have no means of deciding which of two beliefs about the gods, or about ethics, is correct. Because of this, Sextus believes we should suspend judgement. This looks surprisingly like today's moral relativism, which is supposed to be one of the hallmarks of modernity.
It's also interesting that Sextus protects himself from one of the classic cases against scepticism. Some would argue, "Well, if you don't know anything, then how do you know that scepticism is true?" Sextus would respond by saying that he is claiming to have proven that truth is, in general, unattainable. Rather, he would say that, "I'm not claiming to know that truth X is undiscoverable. Rather, I'm arguing that the basis by which people claim to hold X is insufficient."
Sextus is similar to Hume in that he believes skeptics should trust their experiences and the traditions of their society. As far as trusting experience, he does this by creating a sharp dicotomy between sense impression (which deals with externals) and metaphysical theory (which deals with the unseen, and therefore unprovable).