Here, top infant-psychologist Stem (Psychiatry/Cornell Univ. Medical Center; The First Relationship, 1977--not reviewed) creates an imaginary baby's ""diary"" from six weeks to four years, personalizing through lyrical passages of baby-think recent scientific conjecture about how babies perceive. Stem describes a six-week, old infant waking up and staring at a patch of sunshine on the wall beside his crib: ""A space glows over there. A gentle magnet pulls to capture. The space is growing warmer and coming to life. Inside it, forces start to turn around one another in a slow dance."" This is a magic time of life, with everything in the world, even sunbeams, animate and capable of dancing. At about four-and-a-half months, however, the same baby will negotiate a major developmental change. As Stern explains, between three and four months babies begin to sort through the ""invariants"" in their experience; a baby can tell the difference between self and other by registering the blend of sensation, volition, and motion that accompanies his own actions. At 12 months, Stem says, ""Joey"" (his hypothetical baby) ""has stepped into a new world where the center of gravity has shifted from physical events in the here and now to hidden subjective events. . ."" Joey has learned to share his mindscape with another. At about 20 months, Joey's inner world will explode with his discovery of language. Stem wrenchingly describes how the wholeness of sensation and experience can be crashed under the onslaught of words--until finally, at four years old, Joey, now a ""child,"" can narrate his own story. An original, fascinating, and bold re-creation of our earliest experiences, and a moving account of the loss of primal innocence; of special interest to new parents.