One may observe this sort of action, typically shown, in the behaviour of those who are asked to guess a riddle or solve a mechanical puzzle. Some people, of course, set to work deliberately, and think the matter out in all its bearings; they are not here in question. A great many will behave in the manner just described; they will hazard guess after guess in quick succession, and they will snatch at one possibility of solution after another, risking everything upon the impulse that happens to be dominant at the moment, until they either light upon the right principle or ‘give up.’ Professor Lloyd Morgan, one of the best-known writers upon comparative psychology, thinks that this _method of ‘trial and error’_ is characteristic of animal intelligence. The dog, for instance, placed in novel circumstances, meets the situation at once by some action that derives from his individual experience or from racial inheritance; if that first response fails, he ‘tries’ another action, similarly derived; and so on, until luck favours him or he is diverted to something else. Only man advances beyond the stage of ‘trial and error’ to the level of rational selection; and man himself need not; in the story of _Dite Deuchars_ Sir J. M. Barrie draws an accurate picture of human conduct permanently arrested between impulsive and selective action. _Selective action appears when the rival impulses are so evenly matched that no one of them can find direct issue in movement; it implies the state of secondary attention; and it is possible only to organisms that possess free ideas of memory and imagination,—probably, that is, only to man._ Any biography that goes at all minutely into details will furnish examples. Thus, when the first Napoleon was at liberty to turn his thoughts to England, after the treaty of Schönbrunn (1809), he found two possibilities of action: he might himself take in hand the conduct of the war in Spain, or he might devote himself to heightening the rigour of the blockade in the north and north-west. He ‘chose’ the latter course; that is to say, he passed through a period of doubt and hesitation, weighing the alternatives and estimating results,—we know the pattern of secondary attention,—until presently the stronger impulse won. _It is always the strongest impulse that wins_; though here, as also in the case of attention, it is not necessarily the impulse that looks the strongest to psychological observation; there may be a more impressive array of ideas on the side that finally gives way. The winning impulse, as we see in historical examples of selective action, is that which has the strongest backing of nerve-forces (p. 96). The actor, oftentimes, cannot make his action plausible, even to himself, when he tries to state his ‘reasons’; but the sympathetic historian can trace the influence of tendencies which had no mental correlates, and whose existence was therefore unsuspected by their possessor.