If anything, as Gijs van Hensbergen points out in this biography, Gaudi was a post-modernist before his time. The author invokes the fluid forms of Frank Gehry's Guggenheim in Bilbao, and more convincingly the bony organic forms of the Valencia-born architect Santiago Calatrava, as evidence of Gaudi's pervasive and continuing influence. It is true that Gaudi was effectively rediscovered after the Franco regime ended in 1975, just as orthodox modernism was running out of steam and Spain, once again, was searching for a new identity. Gaudi pushed architecture beyond the edge of reason and dangerously close to kitsch. Amazingly, much of it was built. Amazingly, much of it still exists. Worryingly, it was greatly admired by Salvador Dali. Equally worryingly, it was despised by Picasso.

For me, the secular buildings are the most interesting: extreme architecture commissioned by hard-nosed yet indulgent private clients, such as his several buildings and a park for the industrialist Eusebio Guell, or the famous apartment blocks, the billowing Casa Mila and the bony, anthropomorphic Casa Battlo, its stone skin seemingly melting and dripping like wax. No wonder Dali liked it. This is no hagiography, though van Hensbergen is clearly an admirer. Although he remarks that the more deeply religious and withdrawn Gaudi was, the better his architecture, became, he does not skate over his subject's notorious pig-headedness and gracelessness. Not to mention wilfulness: where other architects experimented with models, Gaudi experimented with the actual buildings, tearing down walls that had just been built on site and ordering them built elsewhere, operating generally like a sculptor on what he knew were the absolute structural limits. His clients and contractors needed deep pockets and endless patience.

It's not hard to imagine that Gaudi tapped into some hotline to heaven or hell - where on earth did these unprecedented shapes come from, if not one or the other? For himself, he never claimed direct divine inspiration, though he was prone to deploy increasingly vast and mawkish religious tableaux in his designs - most of which, since few could afford them, we have thankfully been spared.

The stupendously ambitious Sagrada Familia can never be finished, concludes van Hensbergen - or if it is, then its "web of power" will be broken. The act of building it is an act of expiation. One can maybe argue with that view, but one can never argue with Gaudi's last order to his assistant before leaving on his final, fatal walk: "Come early tomorrow, Vicente, so we can make some more beautiful things."