As in ordinary language, metaphors may be used in mathematics to explain agiven phenomenon by associating it with another which is (or is considered tobe) more familiar. It is this sense of familiarity, whether individual or collective,innate or acquired by education, which enables one to convince oneself that onehas understood the phenomenon in question. Contrary to popular opinion, mathematics is not simply a richer or moreprecise language. Mathematical reasoning is a separate faculty possessed by allhuman brains, just like the ability to compose or listen to music, to paint orlook at paintings, to believe in and follow cultural or moral codes, etc. But it is impossible (and dangerous) to compare these various facultieswithin a hierarchical framework; in particular, one cannot speak of thesuperiority of the language of mathematics. Naturally, the construction of mathematical metaphors requires theautonomous development of the discipline to provide theories which may besubstituted for or associated with the phenomena to be explained. This is thedomain of pure mathematics. The construction- of the mathematical corpusobeys its own logic, like that of literature, music or art. In all these domains,an aesthetic satisfaction is at once the objective of the creative activity and asignal which enables one to recognise successful works. (Likewise, in all thesedomains, fashionable phenomena - reflecting social consensus - are used todevelop aesthetic criteria).

　　本書為英文版。