With regard to the _partially_ blind, the question most analogous to the persistence of dream-vision after total blindness, is whether or not the dream-vision is brighter and clearer than that of waking life; whether the sight-centre maintains the full normal power to which it was educated, or whether the partial loss of sight has essentially altered and replaced it. To this rather difficult question I have fewer and less satisfactory answers than to the former inquiry; but the evidence is perfectly in accord with the previous conclusions. Of twenty-three who describe their dream-vision as _only as clear_ as waking sight, _all_ became blind _not later_ than the close of their _fifth year_; while of twenty-four whose dream-vision is more or less markedly _clearer_ than their partial sight, _all_ lost their full sight _not earlier_ than their _sixth year_.[16] The age that marks off those to whom total blindness carries with it the loss of dream-vision from those whose dream-vision continues, is thus the age at which the sight-centre has reached a sufficient stage of development to enable it to maintain its full function, when partially or totally deprived of retinal stimulation. The same age is also assigned by some authorities as the limiting age at which deafness will cause muteness (unless special pains be taken to prevent it); while later the vocal organs, though trained to action by the ear, can perform their duties without the teacher's aid. This, too, is assigned as the earliest age at which we have a remembrance of ourselves. This last statement I am able to test by one hundred answers, collected among these blind persons, to the question, "What is your earliest remembrance of yourself?" The average age to which these memories go back is 5.2 years; seventy-nine instances being included between the third and the sixth years. At this period of child development--the centre of which is at about the close of the fifth year--there seems to be a general declaration of independence of the sense-centres from their food-supply of sensations. Mr. Sully finds sense, imagination, and abstraction to be the order in which the precocity of great men reveals itself; and the critical period which we are now considering seems to mark the point at which imagination and abstraction as permanent mental powers ordinarily come into play. M. Perez likewise recognizes the distinctive character of this era of childhood by making the second part of his "Child Psychology" embrace the period from the third to the seventh year. III