The history of thought does not summarily pronounce: This is true; that is false. Like all history, it has its veiled decisions. It dismantles or embalms certain doctrines, changing them into “messages” or museum pieces. There are others, on the contrary, which it keeps active. These do not endure because there is somemiraculous adequation or correspondence between them and an invariable “reality” – such an exact and fleshless truth is neither sufficient nor necessary for the greatness of a doctrine – but because, as obligatory steps for those who want to go further, they retain an expressive power which exceeds their statements and propositions.