The passive sensation of light had already been blended with muscle sensation in something the same way, by the voluntary movement of turning and focusing the eyes; but that complete seeing which we might call “active sight” is a more complex power than active feeling, and there were other associations yet to be made before it could be fully built up. And I hope it will not spoil the interest of the story of the baby’s sense development if I say here that the plot is going to turn mainly on these two combinations, muscle sense with sight and muscle sense with touch; and then recombination of these two with each other--all welded together by voluntary movements, growing out of involuntary ones. All this time the baby had had a daily source of placid pleasure in listening to chords on the piano--no longer heavy staccato chords, but flowing ones, in the middle octaves. The baby of theory cares for nothing but eating and sleeping; but our baby, even after she was already fretting with hunger, would forget all about it for ten minutes, if one would take her to the piano. Hunger, after it grew really strong, was a sensation that swept all before it; but on the whole, food was a matter of small interest compared with the world of light and touch and sound. As for sleep, the baby slept, from the first, in pretty long periods,--six and seven hours was not uncommon,--and was wide awake between sleeps. At such times she would lie by the half hour, looking peacefully about her, or gazing into our faces with smiles. When we nodded, laughed, and talked to her, her smiles seemed like friendly responses; but this could have meant nothing, except that with our demonstrations those little constellations of high lights and glitters, our faces, bobbed and twinkled in a more amusing manner than ever. At eight weeks old came the final stage in mastery of the mechanism of vision--the power of accommodation, or adjusting the lenses for different distances. It may have been present even earlier: it is a hard thing for the observer to know. But the indications are that it really did happen when I thought, the day the baby was eight weeks old. She was lying on her mother’s knees, fixing an unusually serious and attentive gaze on my face, and would not take her eyes away; indeed, as her mother turned her in undressing, she screwed her head around comically to keep her eyes fixed. At last, after some fifteen minutes, she turned her head clear over, and gazed as earnestly at her mother’s face. To see what she would do, her mother turned her again toward me, and once more she surveyed me for a time, and again turned her head and looked directly at her mother.