Such is also the truceless warfare of the waves on the surface of the sea - BERGSON

"Here, as elsewhere, nature has utilised evil with a view to good. It is more especially the good that has engaged our attention throughout this work. We have seen that the more society improves,the more plastic is the adaptability it obtains from its members; while the greater the tendency towards increasing stability below, the more does it force to the surface the disturbing elements inseparable from so vast a bulk; and thus laughter performs a useful function by emphasising the form of these significant undulations. Such is also the truceless warfare of the waves on the surface ofthe sea, whilst profound peace reigns in the depths below. The billows clash and collide with each other, as they strive to find their level. A fringe of snow-white foam, feathery and frolicsome, follows their changing outlines. From time to time, the receding wave leaves behind a remnant of foam on the sandy beach. The child, who plays hard by, picks up a handful, and, the next moment, is astonished to find that nothing remains in his grasp but a few drops of water, water that is far more brackish, far more bitter than that of the wave which brought it. Laughter comes into being in the self-same fashion. It indicates a slight revolt on the surface of social life. It instantly adopts the changing forms of the disturbance. It, also, is afroth with a saline base. Like froth, it sparkles. It is gaiety itself. But the philosopher who gathers a handful to tastemay find that the substance is scanty, and the after-taste bitter."
extract from "Laughter, an Essay on the Meaning of the Comic" by Henri Bergson