''I''ve been talking to brick walls'' says Lacan, meaning: ''Neither to you, nor to the Big Other. I''m speaking by myself. And this is precisely what interests you. It''s up to you to interpret me.''

These brick walls are those of the chapel at Sainte-Anne hospital. Getting back in touch with his younger years as a junior doctor, Lacan amuses himself, improvises, and lets himself go. The intention is a polemical one: the best of his pupils, captivated by the idea that analysis evacuates all prior knowledge, have been raising the banner of non-knowledge, borrowed from Bataille. No, says Lacan, psychoanalysis proceeds from a supposed knowledge, that of the unconscious. One gains access to it by the path of truth (the analysand ventures to say what comes to mind, frankly and with no frills) when it comes to an end in jouissance (the analyst interprets what the analysand says in terms of libido).

However, two further paths bar access to this one: ignorance (to devote oneself to it with passion is always to consolidate established knowledge), and power (the passion for might obliterates what is revealed by parapraxes). Psychoanalysis teaches the virtues of powerlessness: this, at least, respects the real.

A wise lesson for an era, this era of ours, that has seen bureaucracy, arm in arm with science, dreaming of changing humankind in its deepest reaches - through propaganda, through direct manipulation of the brain, through biotechnology, and even through social engineering. Admittedly things were no better before, but tomorrow they could be far worse.