Page:Popular Science Monthly Volume 11.djvu/612

594 are never performed without thought, although we may be able to group them into classes, and to guide our conduct by general rules or principles, either established by experience or accepted upon the authority of others. The resemblance between these actions and the instinctive ones is recognized in common speech, for we often hear it said of a person who is guided in the main, in this way, by general rules, and is often unable to assign any reason for a particular course of conduct, that he or she is a person of fine natural instincts.

The actions of the sailor, who guides his movements by the weather reports from the Government Signal-Office, without understanding or caring much about the way in which the reports are made out, are still more rational, and further removed from instinct, although they evidently fall into the series, and have much in common with those actions last mentioned. Finally, the actions of "Old Probabilities" himself belong to a still higher class, and are eminently rational.

Reviewing the ground which we have passed over, we find that living things present us with a series of more or less related actions.

First, we have the mechanical and reflex actions of plants and animals; then the instinctive action, then the hereditary habit, then the acquired habit; next the action governed by a general rule, established by experience; and finally the rational action.

Great as seems to be the difference between the two extremes of this series when considered by themselves, it is possible to pass from one to the other through a series of intermediate actions, without the necessity for any great jump in any part of the series; and it is plain that, great as are the differences between them, they all have something in common. Let us try to discover what this something is. All the actions which we have been examining are alike in this, that they are directed to the accomplishment of a purpose. The root grows downward in order that it may reach water. The leaf turns with the sun in order that it may receive a greater supply of heat. The fly-trap closes upon its prey and pours forth its secretion in order that it may be supplied with food. The vine twines in order that its long, slender stem may be supported. The digestive organs perform their various functions that the body may be nourished and its waste supplied. The eyelids close in order that the eye may be shielded from danger.

The chick instinctively seeks its mother that it may be protected and fed; and it hides from the hawk to save its life. The dog begs and the soldier goes through his manual to escape punishment, or to gain a reward or approbation, or perhaps from a combination of all these motives with still higher ones, but in any case to accomplish a purpose. The sailor watches the weather-predictions and regulates his actions accordingly, in order that his voyage may be finished as safely and quickly as possible. And the signal-officer publishes his