It is not work that kills men; it is worry. Work is healthy; you can hardly put more upon a man than he can bear. Worry is rust upon the blade. It is not the revolution that destroys the machinery, but the friction. Fear secretes acids; but love and trust are sweet juices. [ Beecher ]

The common cause of waves is the friction of the wind upon the surface of the water; little ridges or elevations first appear, which by continuance of the force gradually increase until they become the rolling mountains seen where the wind sweeps over a great extent of water. [ F. Marryatt ]