I am reading Then and Now by Somerset Maugham. On the first page Maugham deftly sums up Machiavelli’s thought in 56 well-chosen words:
Machiavelli cherished the conviction that men are always the same and have the same passions, so that when circumstances are similar the same causes must lead to the same effects; and thus, by bearing in mind how the Romans coped with a given situation, men of a later day might conduct themselves with prudence and efficiency.