Light is the lion ...

One may call it mania, madness, or psychosis — a chemical imbalance in the brain — but it presents itself as energy of a primordial sort.

Oliver Sacks reviews Michael Greenberg's Hurry Down Sunshine, a book about his daughter Sally's transformation.

Greenberg likens it to "being in the presence of a rare force of nature, such as a great blizzard or flood: destructive, but in its way astounding too." Such unbridled energy can resemble that of creativity or inspiration or genius — this, indeed, is what Sally feels is rushing through her — not an illness, but the apotheosis of health, the release of a deep, previously suppressed self.

Later, a doctor says to Sally: "I bet you feel as if there's a lion inside you".

The link between mental health and creativity is now a relatively familiar subject. Still, Sacks' compassionate account with its beautiful, unruffled prose is a mood brightener in itself. However, lately, reading with increasing unease the smug, paranoid and irrational assertions on literary and political messageboards and blog comments, I've wondered how much mental illness accounts for online debate and, perhaps more importantly, how much it has silenced.

By the way, if you recognise Greenberg's name but can't place it, he writes an excellent fortnightly column in the TLS.