Historians always have what’s known in the trade as a “source base problem.” Any reconstruction of the past depends on what survives, and since survivals are highly variable (and almost always accidental), most of the things we really want to know will forever remain conjecture. We’re fairly certain what happened, in most cases, but how and why are forever a mystery.
This is especially true when it comes to beliefs, worldviews, ways of living (the academic term d’art for this is mentalités). For instance, you can be pretty sure that the Greeks had a fairly robust conception of the afterlife — every civilization does — but since the sources are largely silent, you get stuff about the Greeks viewing the afterlife as pointless…. which is odd, to say the least, in a culture as concerned with posthumous reputation as the Greeks, but there you have it. Source base problem, see? I’m also pretty sure the Stoics practiced some form of Buddhist-style meditation — given their beliefs, and the Hellenistic world’s well-documented cultural exchanges with India, how could they not? — but since no one has left us an account of Stoic philosophers meditating in an ashram, we can only speculate….
This act of speculation used to be called “the historical imagination,” and back when History was a conservative discipline — as it was, believe it or not, within living memory — it was understood that though all one’s speculations might not make it into the books, the historical imagination was the most important part of the historian’s toolkit. How else is one to make, say, the Greco-Roman world accessible to a bunch of teenagers? A good historian can imagine both his subject and his audience, bridging the gap between the two.
The modern discipline, needless to say, is the exact opposite of that. The genius of Standardized Tests is that they train test-takers to consider only the “givens” of any problem. A well-rounded adult — you know, the kind education was once supposed to produce — would take what he knows about the Greeks, and what he knows about the lack of sources on their beliefs about the afterlife, and conclude that there’s probably a lot more to it.
Modern students, by contrast, “reason” that since Homer is the only source we have, Homer is the only source there is — from which they conclude, NAEP-style, that whatever Homer explicitly said about the afterlife is the sum total of Greek belief about it.
It’s a really swell way to atomize a people, to turn them into the good little consumers globo-techno-socialism requires.