I'm discovering more and more how difficult it can be to discover the absolute truth in history. Here's a simple example from my reading today:
I was going through more of Herodotus and Lycurgus entered the story. He lived in the 700's B.C. and is said to be the Founder of Sparta. This doesn't mean Sparta didn't already exist, it just means that he came and equalized the land ownership and created a communal and militaristic lifestyle for the people. In other words, he is said to have instigated the type of society Sparta was known to have in ancient times.
But once I began to do just the smallest amount of research, the sources were arguing with each other. Some scholars say he never lived, some say he probably did but we don't know much about him, others say we should trust much of what the ancient sources say about him, like Herodotus.
Herodotus mentions that he founded the senate and the ephoralty (a group of magistrates who had power over the king) but the footnote in my book, by the translator says that he didn't found the senate. Then other sources say he didn't found the ephoralty. There's so much disagreement even on the basics about who he was and what he did!
My take on this is that with several sources mentioning him, there must have been such a man and he must have done some of what he is credited with. I don't know if we can ever know exactly what he did and didn't do but I think the best way to approach it is to see what the most ancient sources agree on and go with that.
This approach, of course, requires us to be in the original sources in order to better know the truth. I think that's the right way to come as close to the truth as possible in history.