I think you can only answer this at a point in time - the book you loved at 20 may not carry the same weight at 50. For now, though, I really enjoyed Plutarch'

I think you can only answer this at a point in time - the book you loved at 20 may not carry the same weight at 50. For now, though, I really enjoyed Plutarch's Parallel Lives. He compares the life of an ancient Greek and Roman - EG Alexander vs Caesar.