INSTINCT, according to Hamilton, "s an agent which performs, blindly and Ignorantly, a work of intelligence and knowledge." Brougham says that in stinct is distinguished from reason, in that " it acts without teaching, either from others — that is instruction, or from the animal itself — that is experi ence "; " it acts without knowledge of consequences; it acts blindly, and ac complishes a purpose of which the ani mal is ignorant." In general, we find that instinct and reason prevail in an animal in the inverse ratio to each other. Hence, in man, whose reasoning powers are highly developed, the instincts are few, and manifest themselves principally in children and barbarians. An instinct ive action is performed without any con sciousness, on the part of the agent, of the end which it serves; it is effected as perfectly the first time as at any subse quent period; and is unsusceptible of any adaptation to particular emergen cies; while a reasonable action, on the contrary, is one which always implies a consciousness, on the part of the agent, of the end in view—which becomes only progressively perfect, and which is cap able of being variously modified accord ing to existing circumstances.
Three classes of theories have been proposed to account for the instinctive actions: 1. The physical, which makes them depend on the structure and or ganization of the animal. 2. The psychical, which regards them as the re sult of mental powers or faculties possessed by the animals, analogous to those of the understanding in man. 3. The supernatural, which views them as workings of an intelligence superior to man, or the Supreme Being.