Ways of Seeing, John Berger, page 84, paragraph 2

The term oil painting refers to more than a technique. It defines an art form. The technique of mixing pigments with oil had existed since the ancient world. But the oil painting as an art form was not born until there was a need to develop and perfect this technique (which soon involved using canvas instead of wooden panels) in order to express a particular view of life for which the techniques of tempera or fresco were inadequate. When oil paint was first used - at the beginning of the fifteenth century in Northern Europe - for painting pictures of a new character, this character was somewhat inhibited by the survival of various medieval artistic conventions. The oil painting did not fully establish its own norms, its own way of seeing, until the sixteenth century.

Penguin Books, 1977, New York, 0-14-021631-6