307. I am not indeed here assuming that the faculty which is at the service of the man of genius is of a kind different from that of common men, in such a sense that it would need to be represented by a prolongation of either end of the conscious spectrum. Rather it will be represented by such a brightening of the familiar spectrum as may follow upon an intensification of the central glow.

The solar spectrum itself, as all know, is by no means a uniform or continuous band of coloured light. It contains many dark lines, where some element held in vaporous suspension absorbs the special line of light which the still hotter vapour of that same element characteristically emits. Still more dimmed and interrupted are the spectra of some other stars. Bands and bars of comparative darkness stud their dispersed light. Even thus the spectrum of man's conscious faculty is not a continuous but a banded spectrum. There are groups of the dark lines of obstruction and incapacity, and even in the best of us a dim unequal glow.

It will, then, be the special characteristic of genius that its uprushes of subliminal faculty will make the bright parts of the habitual spectrum more brilliant, will kindle the dim absorption-bands to fuller brightness, and will even raise quite dark lines into an occasional glimmer. But if, as I believe, we can best give to the idea of genius some useful distinctness by regarding it in some such way as this, we shall find also that genius will fall into line with many other sensory and motor automatisms to which the word could not naturally be applied. Genius represents a narrow selection among a great many cognate phenomena; - among a great many uprushes or emergences or subliminal faculty both within and beyond the limits of the ordinary conscious spectrum.

It will be more convenient to study all these together, under the heading of sensory or of motor automatism. It will then be seen that there is no kind of perception which may not emerge from beneath the threshold in an indefinitely heightened form, with just that convincing suddenness of impression which is described by men of genius as characteristic of their highest flights. Even with so simple a range of sensation as that which records the lapse of time there are subliminal uprushes of this type, and we shall see that a man may have a sudden and accurate inspiration of what o'clock it is, in just the same way as Virgil might have an inspiration of the second half of a difficult hexameter.

308. For the purpose of present illustration of the workings of genius it seems well to choose a kind of ability which is quite indisputable, and which also admits of some degree of quantitative measurement. I would choose the higher mathematical processes, were data available; and I may say in passing how grateful I should be to receive from mathematicians any account of the mental processes of which they are conscious during the attainment of their highest results. Meantime there is a lower class of mathematical gift which by its very specialisation and isolation seems likely to throw light on our present inquiry.

During the course of the present century, - and alas! the scientific observation of unusual specimens of humanity hardly runs back further, or so far, - the public of great cities has been from time to time surprised and diverted by some so-called "calculating boy," or " arithmetical prodigy," generally of tender years, and capable of performing " in his head," and almost instantaneously, problems for which ordinary workers would require pencil and paper and a much longer time. In some few cases, indeed, the ordinary student would have no means whatever of solving the problem which the calculating boy unriddled with ease and exactness.

The especial advantage of the study of arithmetical prodigies is that in their case the subjective impression coincides closely with the objective result. The subliminal computator feels that the sum is right, and it is right. Forms of real or supposed genius which are more interesting are apt to be less undeniable.

An American and a French psychologist1 have collected such hints and explanations as these prodigies have given of their methods of working; methods which one might naturally hope to find useful in ordinary education. The result, however, has been very meagre, and the records left to us, imperfect as they are, are enough to show that the main and primary achievement has in fact been subliminal, while conscious or supraliminal effort has sometimes been wholly absent, sometimes has supervened only after the gift has been so long exercised that the accesses between different strata have become easy by frequent traversing. The prodigy grown to manhood, who now recognises the arithmetical artifices which he used unconsciously as a boy, resembles the hypnotic subject trained by suggestion to remember in waking hours the events of the trance.

In almost every point, indeed, where comparison is possible, we shall find this computative gift resembling other manifestations of subliminal faculty, - such as the power of seeing hallucinatory figures, - rather than the results of steady supraliminal effort, such as the power of logical analysis. In the first place, this faculty, in spite of its obvious connection with general mathematical grasp and insight, is found almost at random, - among non-mathematical and even quite stupid persons, as well as among mathematicians of mark. In the second place, it shows itself mostly in early childhood, and tends to disappear in later life; - in this resembling visualising power in general, and the power of seeing hallucinatory figures in particular; which powers, as both Mr. Galton's inquiries and our own tend to show, are habitually stronger in childhood and youth than in later years. Again, it is noticeable that when the power disappears early in life it is apt to leave behind it no memory whatever of the processes involved.

And even when, by long persistence in a reflective mind, the power has become, so to say, adopted into the supraliminal consciousness, there nevertheless may still be flashes of pure "inspiration," when the answer "comes into the mind" with absolutely no perception of intermediate steps.

1 Professor Scripture in the American Journal of Psychology, vol. iv., No. I, April 1891; Professor Binet in the Revue Philosophique, 1895. Professor Binet's article deals largely with Jacques Inaudi, the most recent prodigy, who appears to differ from the rest in that his gift is auditile rather than visual. His gift was first observed in childhood. His general intelligence is below the average. Another recent prodigy, Diamanti, seems, on the other hand, to be in other ways quick-witted.