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readily or with difficulty seems to depend far more upon the local peculiarity of the region of the ear than upon the quality of the brain in general. Moreover the rule is totally different for musical and articulate sounds; the one requires the nerves to be very susceptible to the quality of pitch, the other to articulate differences, these having nothing to do with pitch. There is a third quality of sounds, namely, cadence or accent in spoken language, distinct from either of those, and appealing to a distinctive susceptibility. This last quality I imagine to be related to the muscular sensibility of the ear. These three properties are the bases of three different susceptibilities,— music, languages, oratorical effect. Although previous to practice the ear can distinguish nothing, yet some ears are so constituted as to fall very soon into one line of discrimination, as the musical or the oratorical, while they come very slowly into another. All other things being the same, the length of repetition requisite measures the obtuseness, slowness, or defective plasticity of the ear and its connected circles. We call an ear quick that needs few repetitions.

In acquiring words and sentences, it is difficult to separate the action of the voice (which is true also in some degree of music), and therefore I do not discuss at this stage the whole class of lingual acquirements. But the adhesiveness of the ear for sounds possessing the articulate properties is one of the elements of the case.

23. Cohering trains and aggregates of the Sensations of Sight make, more than any other thing, perhaps more than all other things put together, the material of thought, memory, and imagination. The vocal trains of articulate speech are next in importance as furnishing the matter of the intellectual operations. That process of employing one sense as a substitute for others, avails itself principally of vision, the most retentive of them all. Thus it is that objects thought of on account of their taste or smell, are actually conceived under their visual aspect. The image of a rose dwells in the mind as a visual picture, and in a very inferior degree as a perpetuated impression of a sweet odour.

Sensations of sight, as we have seen, are compounded of

visual spectra and muscular feelings. A visible picture is, in fact, a train of rapid movements of the eyes, hither and thither, over luminous points, lines, and surfaces.

The education of the eye goes through all the stages described for the other senses. There is first a fixed set or familiarity with certain Colours, the result of repetition, enabling their impression to endure in the absence of the original, and to exist at any time of their own accord when once suggested. On this is based the power of discrimination of colours and shades of colour, with sense of difference and agreement, which we have noted, again and again, as the first and lowest consequence of the mental persistence of sensations. But in the eye, sooner than in any other sense, are these various effects accomplished. The optical impressions, from the outset, more readily sustain themselves in the circles of the eye and the brain than the impressions of touch, smell, or taste. The impact of light is apparently a fine and gentle influence upon the nerve, which may be kept up with the lowest expenditure; and the currents originated by it are more liable to be prolonged than in the other senses. Hearing is a more delicate contact than touch, while touch itself is less rude than the concussion of nerve caused by a sapid body on the tongue; but light gives the most delicate impulse of all, and yet that impulse can sustain itself, and produce very keen emotion. These qualities impart to the sense of sight its distinguished place among the organs that connect us with the outer world.

The influence that gives the optical currents a facility in being induced and continued, so as to make one colour, as green, an object of comparison with other colours, is doubtless the same plastic power that forms aggregates of coloured expanse, connecting together a succession of tints, as a rainbow, or an optic spectrum. By passing repeatedly through the successive colours, the impression of one comes to induce the next, and that the following, and so on in order. But we can scarcely advance a step in this illustration without bringing in the movements of the eye, and the feelings belonging thereto. I can suppose a case where the eyes, in a

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state of rest, have before them a number of colours produced in a fixed succession, flash after flash-red, orange, green, blue, violet, white, black, &c.-in which case a train of pure optical impressions would become fixed in the mind, and the occurrence of the first would tend to revive an image of the second, third, &c., on to the last. The gradations of daylight and darkness are associated in this way. But in the ordinary case of associated colours, they exist side by side, as the colours of the landscape, and here we move the eyes to see them, and thereby incorporate the act and feeling of Movement with the sensations of light. If the eye is in this way habituated to a train of colours, the habituation consists in this, that with each colour are associated both a movement of the eye and a second colour, and with this last movement and colour are connected a third movement and a new colour, and so on to the limit of the picture. If we suppose, for example, a chain of fields of different length and varying tints; the eye first sweeps over a yellow corn field, then passes to a grass field of double the length, then to a plantation of wood still longer; the image of the first is an impression of yellow accompanied with a definite sweep of the eye, and a corresponding continuance of the yellow impression; the image of the second is a green effect, doubly prolonged, or accompanied with a double sweep of the eye, or the head, or both; the third image is a different tint of green, imbedded in a still wider muscular sweep. In these circumstances, and after due repetition, if the eye is possessed of the proper yellow hue along with the definite movement of the eye accompanying it, the image of the first field will be reinstated, and the mental movement set, as it were, in an old and accustomed groove, and there will be a transition from the optical impression of yellow and a given expanse, to the optical impression of a shade of green with a double movement, and, lastly, to another shade of green with a still greater movement. These impressions will be reinduced one after another upon the cerebral regions where sensations of sight go their rounds, by the force of the adhesive or transition force of contiguity.

Let us pass from this general illustration to some more specific and typical cases. In order to exemplify the class of Outline Forms, we will suppose a ring or a circle. Here we have a line of light and a round sweep of the eye concurring in one impression. The eye following the ring is receiving a continuous impression of light while performing a round movement; an optical and a muscular impression are conjoined in the effect, the muscular predominating; for the colour of the circumference is supposed merely sufficient to give the lead to the ocular movement. The fixing of the impression depends almost exclusively on the durability of muscular impressions in the muscles of the eye, and in the various circumstances that favour the cohesion in this instance. This case of the

ring typifies a large class of forms employed in various purposes; including all the figures or diagrams of Geometry, the letters of written language, the cyphers or symbols of Algebra, Chemistry, and other sciences, the diagrams and plans of Builders, Engineers, and others. In all these cases the endurance of the object is a muscular effect, measured and determined by the muscular persistence or tenacity belonging to the moving apparatus of the eye.

To specify the precise organs whence the different kinds of talent and acquirement take their rise, is one of the most interesting and curious of the aims of mental science. We will dwell a little longer on this case of the engraining of simple forms and outlines. The cohesive effect of course depends in a great measure on the amount of repetition, but it is always important for us to note what those other circumstances are that render a less amount of repetition necessary, or, in other words, quicken the pace of the acquirement. Now of the innate qualities that hasten the plastic operation, I am disposed to single out two as the chief, or to divide the action into two stages. The one condition is the natural adhesiveness of the muscular impressions in the body in general and of the eye in particular; the other is the tendency to concentrate cerebral power upon a particular subject. I hold that there are good grounds for this distinction, and indeed that it is quite necessary in order to account for the differences that

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we find among individuals as respects the acquisition of forms.

That there is a real difference of natural adhesiveness in different constitutions I assume as a decided fact; nothing less being able to account for the enormous differences observable in the acquirements of persons similarly situated. In the present instance, the adhesiveness is principally muscular, and located in the eye. I do not say that it is a quality of the muscles purely; it belongs rather to the entire circles of nerve concerned in the movements of vision. Some persons can with more ease than others retain the impression of a muscular sweep of any kind, a circle, a square, an alphabet, an expanse, a building; fewer repetitions are necessary in order to make it self-existent to a certain pitch of vividness. Without any special concentration of mind, there is an unequal facility in maintaining the ideas of figure and outline.

With respect to the second point, namely, the differences of cerebral or mental concentration, we may illustrate it thus. There are three distinct classes of outline forms that would be all equally retainable so far as concerns the visual circles, but are nevertheless very differently retained in different constitutions. The muscular sensibility ought to be equally impressed with all kinds of form, seeing that it is the same effect in all; but in reality we find that taking minds in general this is not so; the same mind is not equally retentive of the forms of Euclid and the forms of an artistic design; a difference that must be explained by some circumstance deeper than the circles of vision. The three kinds of figure that I allude to are, symmetrical or mathematical forms, artistic forms, and arbitrary or neutral forms, as the characters of an alphabet, or the chance shapes of irregular objects. To make the brain peculiarly susceptible to some one of these kinds of form, there is wanted a special concentration of energy over and above the natural adhesiveness of the circles of vision. This concentration is due to some special attraction there is for one particular species in consequence of the secondary character belonging to it; in the case of Artistic forms it is the feeling of artistic effect powerfully manifested

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