black curtain, holding each one not more than a fraction of a second. Many persons have been benefited by re membering all the letters of the alphabet in turn perfectly black. Others prefer to shift from one small black object, such as a period or a small letter, to another, or to swing such an object in a manner to be described later (see Chapter XV).
In some cases the following method has proved suc cessful: When the patient sees what he thinks is a per fect black, let him remember a piece of starch on this background, and on the starch the letter F as black as the background. Then let him let go of the starch and re member only the F, one part best, on the black back ground. In a short time the whole field may become as black as the blacker part of the F. The process can be re peated many times with a constant increase of blackness in the field.
In one case a patient who saw grey so vividly when she palmed that she was positive she saw it with her eyes, instead of merely imagining it, was able to oblit erate nearly all of it by first imagining a black C on the grey field, then two black C's, and finally a multitude of overlapping C's.
It is impossible to remember black perfectly when it is not seen perfectly. If one sees it imperfectly, the best one can do is to remember it imperfectly. All persons, without exception, who can see or read diamond type at the near-point, no matter how great their myopia may be, or how much the interior of the eye may be diseased, become able, as a rule, to see black with their eyes closed and covered more readily than patients with hyperme-tropia or astigmatism; because, while myopes cannot see anything perfectly, even at the near-point, they see