Or how about 500 volunteers, each equipped with a shovel, forming a single line and replacing by 10 cm the dune they're standing on (When Faith Moves Mountains)? A man walking in circles, and every time he has completed a tour, a sheep is added in a line behind him: the circle is closed with sheep number 23 (Patriotic Tales)?

All these actions have been induced or performed by Francis Alÿs and in themselves they were a clear artistic articulation. But they have been ‘saved' for prosperity by turning them into video installations. A generous overview of these videos forms the basis for A Story of Deception.

Alÿs likes - or at least his critics like (since he's reluctant to talk to the press) - to stress the political underpinning of his works: Patriotic Tales refers to a key phase in the Mexican student protests of 1968; Paradox of Praxis I comments on the imbalance between effort and result in daily life in Latin America; and Rehearsal I should be seen as "an allegory of the struggle of Latin American societies to adjust to the social and economic expectations of their northern neighbours".

But honestly, I wouldn't have known all this if I hadn't read it in the excellent book, also called A Story of Deception, which accompanies the exhibition. More than just a catalogue, it gives an overview of Alÿs' work to date. But, although this knowledge does add an extra dimension to his work, it's not necessary to appreciate it. On the contrary, I would say, because it might narrow the works down to something too specific. Without this knowledge, they stay poetic mysteries, based on the hypnotic power of repetition.

Indeed, repetition may be the weakness of a lot of video art; far too many artists think that if they just keep repeating an action it becomes interesting art. Alÿs fortunately doesn't fall into that trap; the subjects he chooses and the way he films them leave the viewers spellbound and, at least for me, that, ultimately, is the power of his art.

One installation is overtly political: The Green Line. Alÿs walked the border between East and West Jerusalem, carrying a dripping can of green paint. Two days and 58 litres later, he's back at his starting point. Shortly thereafter, a video of his journey was shown to selected people who were asked to comment. Their comments, varying from musings on art to the history of the state of Israel, combined with the original video, form this impressive installation.

Alÿs' penchant for repetitiveness is also present in the other works: Camguns is a series of fake wooden rifles constructed with film rolls. And the amazing, both disquieting and touching, Le temps du sommeil is a collection of 110 (and counting) small paintings. At first glance, they seem very similar but, admired at close range, they start to look very different.

Along with repetition, collecting is one of the cornerstones of Alÿs' intriguing art. This aspect remains underexposed in this exhibition, but it would be petty to criticise the curators for this, since what is present forms a very coherent unity.

If you want to see every video from start to end - and I can recommend this for most of them - you'll need a whole afternoon to savour this exhibition. That seems a lot, but it guarantees an overwhelming experience. But be warned: Alÿs' images will still be haunting you, long after you've left Wiels.

Until 30 January
Wiels
Van Volxemlaan 354, Brussels
www.wiels.org