The drops of water in a fountain go up, some higher, some lower, some go a very little way, some rise very high. When each drop falls down it sinks into the stream, flowing away with it, and does not rise again, although the water of the same stream rises again and falls again in drops, which proves to us the fact that it is the water which rises and falls continually, not the drop; yet apparently it rises and falls as drops, though the portion of water in every drop is different.