bushbush said:A lot of accounts are often from a single source. For example, much of tales during the last days of the Republic are from the letters and works of Cicero, whose work were perserved cuz he was name a righteous pagan.
Actually the last days of the Republic is one of the best covered eras in Roman history because several active players and eyewitnesses have written about it, Cicero's letters which includes numerous letters to Cicero as well written by all the major figures, Caesar, Sallust and Lucan. Then add the later sources written about the era based on sources we dont have anymore (ex. like Florus' account based on the lost account by Livy, or Appians work) there is so much to go from that some events can actually be followed on a day-to-day basis.