THE INFLUENCE exerted by classical models on the art of the middle ages has been studied in a number of books and articles, and allusions to it are a commonplace in the histories of different periods in medieval art. For the most part, however, the difficulty of distinguishing such influences precisely, and of tracing them to any particular group of works, has been accepted as insuperable, and critics have been content simply to classify what they have noticed as due to some survival of 'the antique': a phrase which might have reference to works produced in classical or Hellenistic Greece, and equally to those of the age of Constantine or of the classical revivals that are manifested in Byzantine art at a still later period. There is some reason for this lack of precision. Much of the work done has been iconographical studies; and it is particularly difficult to be certain about the form in which an iconographical pattern reached the artist who adopted it (128, 129). The formulae turn out to have been used very widely, and to say that a craftsman drew his version of them from this or that source would generally be hazardous. Thus it is seldom possible to defend the assertion of classical inspiration on iconographical considerations alone. And when points of technique or of style begin to be taken into account, subjective impressions are bound to play a part in the critic's judgment, and perhaps make havoc of it. Nevertheless, if the revival of interest in the antique that is shown from time to time by artists of the middle ages is to be understood, some attempt must be made to discover on what that interest was from time to time based. This is prerequisite to the study of the revival of classical art forms in the renaissance.
In the history of scientific and literary ideas the general pattern of classical revival, though complex, is becoming comparatively clear. This result has been achieved by detailed investigation of the surviving books, libraries and library catalogues of various periods, by the analysis of the sources on which medieval authors drew, and by enquiry whether they drew on them at first or second hand. When a