After having traced it to its origin, we shall have to follow its evolution, which passes through three principal phases: the first, utilitarian and practical; the second, disinterested and scientific; in the third, which is much less frequent, it attains the power and exclusiveness of a passion.
I. This feeling, like all the others, depends on an instinct, a tendency, a craving; it expresses in consciousness its satisfaction or non-satisfaction. This primitive craving—the craving for knowledge—under its instinctive form is called curiosity. It exists in all degrees, from the animal which touches or smells an unknown object, to the all-examining, all-embracing scrutiny of a Goethe; from puerile investigation to the highest speculations; but whatever may be the differences in its object, in its point of application, in its intensity, it always remains identical with itself. Those devoid of it, such as idiots, are eunuchs in the intellectual order.
Assuming this innate craving, how is it developed during the first period?
The first stage is that of surprise. It appears early in the child; quite clearly, at latest, in the twenty-second week, according to Preyer. It is a special emotional state which cannot be traced back to any other, consisting of a shock, a disadaptation. In my opinion, its special and peculiar character lies in its being without contents, without object, save a relation. Its material is a relation, a transition between two states—a mere movement of the mind, and nothing more. The mode of expression and the physiological accompaniments of surprise are very clearly defined. The description of these will be found in Darwin (Expression of the Emotions, ch. xii.); the eyes and mouth are wide open, the eyebrows raised, the sudden shock is followed by immobility, the pulsations of the heart and the respiratory movements are accelerated, etc.
The second stage is that of wonder. I think with Bain and Sully,[[229]] that the distinction between these two stages is not a vain subtlety. Surprise is momentary, wonder is stable; one is a disadaptation, the other a readaptation; one is without objective material, the other has for its material some strange or unaccustomed object. It is this second stage, no doubt, which Descartes called admiration, and which he placed among his six primary passions:—"Admiration is a sudden surprise of the soul which leads it to consider with attention the objects which appear to it rare and extraordinary."[[230]] In fact, wonder is the awakening of the attention, of which it has the principal characteristics—unity of consciousness, convergence towards a single object, intensity of perception or representation, adaptation of movements.[[231]] In the beginning, before wonder is accompanied by pleasure (or pain, as the case may be), it has a peculiar character approximating to what we have called the neutral state, or that of simple excitation.
The third stage is that of interrogation, of reflections succeeding to the consternation produced by the first shock. This is the stage of curiosity properly so called, which consists in two questions, put implicitly and explicitly: What is that? What is the use of it? What is the concrete nature of this object? and what can be its utility? Primitive peoples, children, animals, incessantly put to themselves this double question; not, certainly, in clear and analytical terms, but instinctively and by their actions. The dog, brought face to face with an unknown object, looks at it, smells it, approaches, withdraws, ventures to touch it, returns, and begins again; he is pursuing this investigation after his own fashion; he is solving a double problem of nature and utility.[[232]] The interrogation consists in assimilating the new object to our former perceptions or representations—classing it, in fact.
Is primitive man curious? Herbert Spencer alleges a large number of facts in proof of his distaste for novelty.[[233]] However, the craving for knowledge seems to be very unequally distributed among the various races; the only universal fact appearing to be that primitive curiosity is limited to very simple things, all of which have, or seem to have, some practical utility. Curiosity and the emotional state which accompanies it have no other end than the preservation of the individual—just as we have seen with regard to the tendency to live in communities, or to revere the gods, in this same initial period of evolution. To be wide awake, to make inquiries as to what will help or harm one, in a word, knowledge in the practical order, is a powerful weapon in the struggle for life; a cause of selection in favour of the curious, and at the expense of the incurious. It is the survival of this entirely utilitarian curiosity which explains why, at the present day, uncultured and even semi-civilised peoples object to the entrance into their country of travellers from a distance for the purpose of geological or other scientific explorations; they are always suspicious of a search for treasure, of espionage, or of some unknown ill deed on the part of the strangers.
II. How did the transition to the disinterested period come about? We may admit, with Sully,[[234]] that this took place through the natural, innate inclination of the human intellect towards the extraordinary, the strange, the marvellous. The same tendency which, under its creative form, engenders religious, poetical, social myths, attempts under the form of research to discover instead of imagining causes.[[235]]
We are here at the point of junction between the æsthetic and the intellectual sentiments, which will presently bifurcate, and pursue each its own course. This inquiry is only half disinterested, however, for if man tries to penetrate the mystery of things it is in the hope of profiting thereby.
For the rest, however this transition may have come about, it took place when the struggle for existence became less keen, and it was possible to cultivate disinterested research for its own sake. Next, curiosity became scientific emotion, and gradually extended itself to every kind of investigation: the intellectual sentiment was formed in all its fulness.