Susannah Frankel: Fashion, philosophy, art: it's all about the frontiers of thought

That intellect and fashion are at polar ends of the cultural spectrum is taken as read to the point where anything that whiffs of pretension is seen as decidedly bad form by even the most brilliant designer.

Yet Yves Saint Laurent, the greatest couturier of the late 20th century, was as indebted to the work of Proust, Braque, Picasso and Mondrian as he was to the fashions of the street.

Miuccia Prada, among contemporary fashion's most potent forces, completed a PhD in political science before agreeing, reluctantly, to take over the family business. The now retired Modernist Helmut Lang put down his scissors and pins to become a fine artist.

Of course, to label a look as "intellectual" may be rushing in where angels fear to tread – Prada's fashions were initially explained in that way, as indeed were those by the Comme des Garçons designer Rei Kawakubo. That was because people didn't understand them, though. So far from conventionally glamorous were the aesthetics involved that an entire new vocabulary was reached for to describe them.

That is not to say that the minds behind the clothing in question couldn't keep up with the best of them. "For me to sit down and sketch quietly is a luxury," argues Karl Lagerfeld, neatly nailing the prevailing mood. A fashion designer is far more than an indulged and indulgent, hyper-colourful creator residing, resplendent, in a gilded cage. The finest fashion reflects and even predicts the times and requires an understanding of the world that the cerebrally challenged are unlikely to possess.