The Impulse to Power introduction to the book "Power" by Bertrand Russell . Between man and other animals there are various differences, some intellectual, some emotional. One of the chief emotional differences is that some human desires, unlike those of- animals, are essentially boundless and incapable of complete satisfaction. The boa constrictor, when he has had his meal, sleeps until appetite revives; if other animals do not do likewise, it is because their meals are less adequate or because they fear enemies. The activities of animals, with few exceptions, are inspired by the primary needs of survival and reproduction, and do not exceed what these needs make imperative. With men, the matter is... (From : http://www.geocities.com/Athens/Oracle/2528/br_pow....)