The subject I am discussing here deals with a very peculiar kind of knowledge — a kind of knowledge whose means is not concepts and reasoning, but affective inclination or affinity, and which is often disregarded by philosophers interested only in the rational kind of knowing. Henri Bergson liked to quote a sentence he found in the letters of a French philosopher; the sentence was as follows: “I have suffered from this friend enough to know him.” When I know a friend to the core — not through having submitted him to a complete series of psychological tests, but because I have suffered from him and have got in myself the habit of his nature — then we may say in philosophical language that I know this man by connaturality.