How Imagination Cures 151
two eyes are out of focus to the same degree, similar impressions will be made upon the retina of each; but the impressions made upon the mind may be totally un like, whether the eyes belong to the same person or to different persons. If the normal eye looks at an object through glasses that change its refraction, the greyness and blurring produced are uniform and constant; but when the eye has an error of refraction equivalent to that produced by the glasses, these phenomena are non uniform and variable.
It is fundamental that the patient should understand that these aberrations of vision-which are treated more fully in a later chapter-are illusions, and not due to a fault of the eyes. When he knows that a thing is an illusion he is less likely to see it again. When he becomes convinced that what he sees is imaginary it helps to bring the imagination under control; and since a perfect imagination is impossible without perfect re laxation, a perfect imagination not only corrects the false interpretation of the retinal image, but corrects the error of refraction.
Imagination is closely allied to memory, although dis tinct from it. Imagination depends upon the memory, because a thing can be imagined only as well as it can be remembered. You cannot imagine a sunset unless you have seen one; and if you attempt to imagine a blue sun, which you have never seen, you will be come myopic, as indicated by simultaneous retinoscopy. Neither imagination nor memory can be perfect unless the mind is perfectly relaxed. Therefore when the imagination and memory are perfect, the sight is per fect. Imagination, memory and sight are, in fact, coin cident. When one is perfect, all are perfect, and when