Clever youths crave intellectual baubles. They like to toss them about, and then, once broken, they like even more to hurl them from the playpen. One envies, therefore, the students of Bologna University who gathered at the beginning of the 1994-5 academic year to hear Professor Eco deliver ‘The Force of Falsity’, which is the opening essay of his new collection, Serendipities.

Serendipity is here defined as the mechanism by which ‘false beliefs and discoveries totally without credibility could then lead to the discovery of something true’. Whatever ‘true’ or ‘false’ may mean in that formula, Eco takes ‘recorded in the encyclopaedia’ as his criterion of truth, hopes that he has avoided being ‘too dogmatic’, then gets on with the job in hand, which is entertaining the students.

He starts with a quotation (in Latin) from Aquinas’s Quaestio quodlibetalis XII, followed by an anecdote about Saint Thomas chasing a naked courtesan out of his bedroom with a burning stick. Next question: Is the Earth round or flat? The answer is ‘flat’, according to Cosmas Indicopleustes, and ‘round’ according