Only the broken understands what horrors lurk in the unstable mind. What's real, what isn't. The first voice heard that no one else hears leaves the imprint of terror when the realization sets in that there will always be a question to what borders the brink of sanity.
The baby lays in the crib and sees the mobile go around with tiny toys attached. Hearing the annoying voice of mother singing, and the stupidity of daddy's "goochy goo's."
Born without limbs, voice or growth, doesn't make one crazy! Being fifty with parents of eighty, circling a crib certainly seizes sanity.