Autism is a complex, multifaceted disorder that usually becomes evident before a child is two years old. It affects at least four times as many boys as girls. Among itscommon characteristics are avoidance of touching and eye contact, muteness or severely limited speech, repetitive movements like rocking, and a demand for routine. Though autistic children or adults might appear from the outside to be retarded, they are often fully cognizant of all that occurs and is said around them. Those referred to as idiot savant are frequently autistic, with one startling, shining talent - in, for instance, music or mathematics - emerging from an otherwise deserted human landscape.

A crude but effective metaphor for the disorder is that of a cage. It's as if impenetrable, though transparent, barriers exist between autistic people and the rest of the world. However much they might desire to participate in the life around them, something - a powerful, mysterious, invisible force - prevents it.