He was a lonely ghost uttering a truth that nobody would ever hear. But so long as he uttered it, in some obscure way the continuity was not broken. It was not by making yourself heard but by staying sane that you carried on the human heritage.
Man is the only creature that consumes without producing. He does not give milk, he does not lay eggs, he is too weak to pull the plough, he cannot run fast enough to catch rabbits. Yet he is lord of all the animals. He sets them to work, he gives back to them the bare minimum that will prevent them from starving, and the rest he keeps for himself.