One of the things that people ought to consider before trotting out that quote is that Athens fell. Socrates' culture is now long dead. The broad stroke of history may be upwards in many ways, but societies can and have fallen apart. Most of the other cultures you may trot similar quotes out from have also effectively fallen, even if they were not destroyed; Victorian England, for instance, does not rule the world anymore. Rome fell after a protracted period in which it was obvious it was becoming weaker. It doesn't take all that much imagination to look about and conclude that we're in the process of "becoming weaker" too.

I don't think this quote proves what people think it does.