There is a built-in paradox for the Greens: they need to both persuade people that we face major ecological disasters and at the same time hold out hope that we can respond meaningfully to them. To do this requires the sort of corny and touching optimism that gives Bob Brown’s book its title.

Optimism is neither a conventional memoir nor a political autobiography; it is rather a collection of sketches from the life of a man who will be remembered as one of the pivotal figures of Australian politics in the two decades that straddle the new millennium. The style is largely prosaic, excepting moments of real feeling when Brown describes the Tasmanian wilderness and his relationship to it.