“You all see in the matter of coinage, in which it is felt that we have some interest, how we have even invented an art, and how many means the tester employs to test the coinage—sight, touch, smell, finally hearing; he throws the denarius down and then listens to the sound, and is not satisfied with the sound it makes on a single test, but, as a result of his constant attention to the matter, he catches the tune, like a musician.” -Epictetus (on validating #bitcoin blocks)