I found EF Schumacher's `Small is Beautiful - a study of economics as if people mattered' in a secondhand bookshop and bought it because the title really resonated with me. I knew nothing about it at the time, but it turns out it's been a highly influential book in the environmental and social justice movements.
First published in 1973 in the wake of the oil crisis, Schumacher's collection of essays was very formative in the understanding of sustainability. Some of the figures may be out of date, but it remains a passionate and radical view of economics even today, especially in the light of current oil prices, and something of a fulfilment of the resource depletion scenarios he foresaw.
I leave you with a quote:
"An attitude to life which seeks fulfilment in the single-minded pursuit of wealth - in short, materialism - does not fit into this world, because it contains within itself no limiting principle, while the environment in which it is placed is strictly limited."