actual unit of measurement, as a foot, a yard, a mile. A child's mind has no abstract notion of color in the beginning. It is only when the sensations of many colors have been felt, and the differences in these sensations have gradually been perceived, that the intellectual conception of the different shades, as ideas, is at last attained. It is well known that a child must have lived a number of months before it can distinguish the most diverse shades.
This process of impression and sensation, with the establishment of the intellectual images these feelings give rise to, and the emotions of pleasure or pain that ensue, followed by a determination to perform some act in accordance with the pleasure or the pain—produces the development of the mind. There are four constituents: Perception or Sensation; Intellect, or the creation of the mind-image suggested by the sensation; Emotion, or the reflex feeling occasioned by the image; and Will, or the resolve to act. As Dr. Hammond puts the illustration: "A person walking in the street sees a man on the opposite side of the way—this is Perception; he recognizes him as a friend—Intellect; he feels joy at the encounter
