According to the following statements and conditions, a figure or object, without color, would be invisible. Maybe that is why spirit creatures cannot be seen. Accordingly, if something is below perception, subliminal, it cannot be seen or understood. “What is it that having been concealed so long becomes now for the first time visible? What causes one man to see beauty and another to have exactness of visual perception? What is it that makes one person cling to colour while revealing to another the forms? What is it that helps one man while disturbing another, when both endeavour to reproduce a scene or a thought ? Perhaps these differences may be partly explained by the accident of special interests or peculiarities of temperament, which habituate the attention in one way or another. But we do not now inquire into remote causes. The immediate cause consists, doubtless, in the difference in the perception itself.How and in what respect is it possible for vision to change while the object remains identical? The discovery of exercises for cultivating sense-perception depends on this point. Strictly speaking, what the vision perceives in objects is colour. That the object is a solid body, that it is hard or soft, dry or damp, is matter of feeling, not of sight. But colour occupies a place. There are boundaries at which it terminates, or portions where it shades off into other colours. Where an object ceases to show colour it ceases to show itself. At such points are the boundaries of its visible appearance. These boundaries inclose its figure. Sight, then, in addition to colour, shows figure or form,but the latter only by means of the former. With out colour the figure would be empty; it would be nothing.” “If any point in an object is of striking colour or brilliancy the impression on the eye from that point is stronger. At the expense of the unity of apperception, the vision is enticed to that one point. The remainder of the object escapes our perception, if not wholly, at all events partially. The impression made is weak, indistinct, and wavering, unless equilibrium of vision is restored by an especial attention to the whole. Once the vision becomes accustomed to yield to glitter, brilliancy, and variegation, it is lost to a great part of the objects of Nature, and it is wholly lost to taste. In order to confer charms upon anything it will attach to it some thing bright, no matter if by doing so its form is distorted. Man, the most beautiful shape in Nature, is without glitter. In order to be worth looking at he decks himself in gold and purple, the feathers of birds, and opalescent shells. Colour at the expense of form is a characteristic of all tasteless ornamentation. It is easy to call to mind illustrative instances of savage and semicivilized nations, of our own past history, and of much that is not yet past. Clearly, therefore, the cardinal fault of uneducated sight consists in adherence to colour. More exactly speaking, it consists in being immersed in the pre-eminent colour, in losing weaker colours at the instance of the stronger. Correctness of sense-perception, which is opposed to this fault, consists in synthetically connecting everything that pertains to the form of a thing. It is attention to form to which our vision requires to be especially educated. This being gained, the sensations of contrast between light and shadow, and between shades of colour, will come of themselves almost. It will be said, perhaps,that we should mention proportion also; but the proportions are implied in every form actually coming before our eyes.” (Herbart’s ABC Of Sense-Perception And Minor Pedagogical Works, pp 133-135)