The book, thought to have originated on the cultural borders of Italy and Germany, is arguably the most lavishly illustrated medieval manuscript in private hands. Almost 400 exquisite watercolour illustrations, combining a primitive innocence with a confident technique, accompany a secular text packed with practical advice and remedies.
Readers of the Book of Life are told that eating peas helps to produce semen, but is bad for kidney and bladder problems; squash reduces thirst; eggs, of which only the yolk should be consumed, encourage coitus but cause freckles and goose gives courage.
Mr Fogg said: 'The text evokes a medieval world which mingles the most primitive and ancient magic of the witch doctor . . . with the supreme sophistication of the Renaissance kitchen and banquet table.'
However, many of the remedies are as current today as they were in 1470: for example, listening to music helps insomnia and washing with hot water is good for you. The book, in covering every conceivable aspect of life, also paints a picture of daily life in the 15th century.
The price is a healthy pounds 500,000. There are three other versions of the book, but all are in public collections including at the Vatican in Rome, and the Bibliotheque Nationale in Paris.
Sotheby's broke the world record for a drawing by Constable yesterday, selling his view of Helmingham Dell, Suffolk, for pounds 93,300 - more than double its lower estimate. The previous record, set by Sotheby's in 1987, was pounds 57,000. The drawing dates from 1800, the artist's second year at the Royal Academy Schools.