The siblings of children with severe intellectual handicaps grow up differently. Their childhoods are disrupted, as much by witnessing parental distress and frantic searches for causes and cures as by their brother or sister’s weirdness.

Mark Frankland makes no secret of the fact that he found his younger brother Freddie “alien and frightening in a way I did not understand . . . My most constant feeling about him was annoyance at the trouble he caused with his unpredictable, inexplicable behaviour”. Then followed guilt for thinking such thoughts, then considerations of jealousy. But why be jealous of someone for whom (as one expert summed it up) “anxiety, severe despair, and profound unhappiness for no tangible reason are generally preponderant”.

Out of Mark Frankland’s early ambivalence eventually grew compassion and the need to understand and to account for the pattern of Freddie’s life. The result is this extraordinary, lucid biography of a silent man. It begins with the tale of a glamorous woman who sets out to adopt a beautiful baby to replace her dead brother. (This is 1947 when such motives seem to have been perfectly acceptable.) Cautiously, Frankland reveals how beautiful toddler becomes monster-boy, howling, destroying, consuming large quantities of paper, wood, rubber. He is misdiagnosed as schizophrenic, subjected to an inappropriate Kleinian analysis, comes under the wing of Karl Konig, one of the founders of the Camphill communities. But even such an ideal community can’t offer a safe haven for ever. At one point, Mr Frankland senior is threatened with Freddie’s expulsion from the community over an unpaid bill for a trifling amount.

As Freddie matures out of turbulent boyhood into frightening manhood, he is moved from one residential home to another. He is sectioned (because in summertime he likes touching the bare arms of women wearing short sleeves).His mental hospital is closed down, ward by ward, around him. Out of this shambles of a life, Frankland has created a compelling, informative, and ultimately almost hopeful book. If only Freddie could read it, he might discover how much his brother feels for him.

Freddie the Weaver is written by a man on the outside trying to see in. In Dark Hours I Find My Way, is the reverse: a man on the inside of autism trying to get out. Birger Sellin, a young German with no effective speech or use of language, was recently introduced to “assisted communication”, the controversial method of using a keyboard with a helper to hold your fingers steady over the letters. The result is an astonishing stream of “messages from an autistic mind”.

Many are repetitive, confusing, downright sad. But there also emerge flashes of harmony and clarity. “A skyblue fabulous primeval wish of all autistics is to give up their isolation and loneliness and be recognised as a social species we want to be autistic in such a way that you normal people will feel it is interestingly exotic and it won’t get on your nerves”.