"In the early and high Middle Ages it had been possible to spend many tens and even hundreds of years on erecting a single building... This was possible because human life was regarded as primarily the life of the community in which one generation quietly succeeded another... All this was destined to change in the late Middle Ages and Renaissance period. Even in painting the time factor made itself felt... causing painting a secco to replace al fresco... since the very long apprenticeship... could not be maintained, and a successful painter had to work fast..."