I think one of the advantages of reading very old material is a) it's not bogged down by modern ideology, b) imparting the realization that some human issues and ideas have been around a very long time (see for instance dialogues in Thucydides History of the Peloponnesian War), b) some ideas and insights have a timelessness to them. Take for instance the Tao Te Ching. I found it retains influential power, despite my not being completely on board.