The crucial point in man’s mathematical history came when more than patterns were required; when more was needed than to look inside the cave to assure himself that both children were present, or a glance at his rack of stone axes to convince himself that all four spares were in place.
At some point, man found it necessary to communicate numbers. He had to go to a neighbor and say, “Listen, old man, you didn’t lift one of my stone axes last time you were in my cave, did you?” Then, if the neighbor were to say, “Good heavens, what makes you think that?” it would be convenient to be able to say, “You see, friend, I had four spares before you came to visit and only three after you left.”
~ Isaac Asimov, Realm of Numbers, pp. 1-2