Memory a Measure of Relaxation 137
available than any other color. There is nothing blacker than printer's ink, and that is practically ubiquitous. By means of the memory of black, therefore, it is possible to measure accurately one's own relaxation. If the color is remembered perfectly, one is perfectly relaxed. If it is remembered almost perfectly, one's relaxation is almost perfect. If it cannot be remembered at all, one has very little or no relaxation.
By means of simultaneous retinoscopy, these facts can be readily demonstrated. An absolutely perfect memory is very rare, so much so that it need hardly be taken into consideration; but a practically perfect memory, or what might be called normal, is attainable by every one under certain conditions. With such a memory of black, the retinoscope shows that all errors of refraction are cor rected. If the memory is less than normal, the contrary will be the case. If it fluctuates, the shadow of the retino scope will fluctuate. The testimony of the retinoscope is, in fact, more reliable than the statements of the patient. Patients often believe and state that they remember black perfectly, or normally, when the retinoscope indicates an error of refraction; but in such cases it can usually be demonstrated by bringing the test card to the point at which the black letters can be seen best, that the memory is not equal to the sight. That the color cannot be re membered perfectly when the eyes and mind are under a strain, the reader can easily demonstrate by trying to remember it when making a conscious effort to see-by staring, partly closing the eyes, frowning, etc.-or while trying to see all the letters of a line equally well at one time. It will be found that it either cannot be remem bered at all under these conditions, or that it is remem bered very imperfectly.