Eco-art exhibitions are part of the trend of our times. Radical Nature, the show at the Barbican Art Gallery in London, demonstrated some of the possibilities and paradoxes of enterprises of this sort. Basically what the organizers had to do is to move the outside indoors. This set them both practical and, in their own terms at least, moral problems.

The Barbican Art Gallery was right at the top of a great hulking post-Corbusier building. You could only get there by using an elevator. The spaces were completely enclosed, which means artificial ventilation as well as artificial lighting. In this sense, the building felt like a paradigm of all the things that the contemporary prophets of an ecological revolution most deplore. Quite a number of the exhibits featured growing plants, which had to be kept alive in this setting by using energy-expensive means.

To be fair, the point was specifically made in the exhibition itself. It featured a presentation by the veteran artists Newton Harrison and Helen Mayer Harrison - a version of their Survival Series of 1970-72, a group of works intended to teach techniques for self-sustainable living. Basically, this version was an indoor farm split up into a series of containers, each about four times the size of a large window box.