Because this particular block of ice (a geometrically perfect Bauhaus iceberg) is very beautiful. Its beauty is ethereal and uncertain, changing from moment to moment and captivating visitors who, on first encountering it, seem ready to walk out as if tricked by the artist into wasting their weekend.
Anya Gallaccio, the artist who made it (with a little help from strong and warm-blooded workmen), is quietly obsessed with notions of change and decay, employing an unlikely palette of perishable materials over the past few years that includes melting chocolate and fading daisies. She took part in the "Freeze" show (a Pandora's box of installation art by young artists, which put Damien Hirst on the map) held in this same building in 1988.
The process of change and decay in Gallaccio's latest installation is abetted by a large and irregular rock of natural salt eating its way, like some voracious alien, through the depth of the ice block. Reacting with the ice, this weaves fascinating crystalline patterns through the frozen water; by the end of this month it should have bored a hole right through the ice.
The block was made at the beginning of this month and is expected, assuming the cold spell lasts, to witness its end. Until then, visitors can expect to see a strangely chilling artwork on auto-destruct passing through fascinating phases of pattern, texture and colour. On Sunday, the block glowed in a seemingly infinite palette of pale blues. Close up, of course, these phantom blues vanished, for ice has no colour.
In this sense, Gallaccio's block is truly like an iceberg, ethereal yet solid, solid yet continually eroding, steeped in colour yet possessing no colour, and with a beauty all but impossible to capture on celluloid or canvas.
Although the last thing you might feel like on a cold morning is a trip to an ice box, go before those 34 tons of ice melt into the Docklands' air.
n 'Intensities & Surfaces' is at Wapping Pumping Station, Glamis Road, London E1 (0171-379 9700) 16- 18 and 23-25 Feb