of art and discovering how far that movement keeps pace with changes in the spiritual state of society.  My view of the rise, decline and fall of art in Christendom is based entirely on a series of independent aesthetic judgments in the rightness of which I have the arrogance to feel considerable confidence.  I pretend to a power of distinguishing between significant and insignificant form, and it will interest me to see whether a decline in the significance of forms—­a deterioration of art, that is to say—­synchronises generally with a lowering of the religious sense.  I shall expect to find that whenever artists have allowed themselves to be seduced from their proper business, the creation of form, by other and irrelevant interests, society has been spiritually decadent.  Ages in which the sense of formal significance has been swamped utterly by preoccupation with the obvious, will turn out, I suspect, to have been ages of spiritual famine.  Therefore, while following the fortunes of art across a period of fourteen hundred years, I shall try to keep an eye on that of which art may be a manifestation—­man’s sense of ultimate reality.

To criticise a work of art historically is to play the science-besotted fool.  No more disastrous theory ever issued from the brain of a charlatan than that of evolution in art.  Giotto did not creep, a grub, that Titian might flaunt, a butterfly.  To think of a man’s art as leading on to the art of someone else is to misunderstand it.  To praise or abuse or be interested in a work of art because it leads or does not lead to another work of art is to treat it as though it were not a work of art.  The connection of one work of art with another may have everything to do with history:  it has nothing to do with appreciation.  So soon as we begin to consider a work as anything else than an end in itself we leave the world of art.  Though the development of painting from Giotto to Titian may be interesting historically, it cannot affect the value of any particular picture:  aesthetically, it is of no consequence whatever.  Every work of art must be judged on its own merits.

Therefore, be sure that, in my next chapter, I am not going to make aesthetic judgments in the light of history; I am going to read history in the light of aesthetic judgments.  Having made my judgments, independently of any theory, aesthetic or non-aesthetic, I shall be amused to see how far the view of history that may be based on them agrees with accepted historical hypotheses.  If my judgments and the dates furnished by historians be correct, it will follow that some ages have produced more good art than others:  but, indeed, it is not disputed that the variety in the artistic significance of different ages is immense.  I shall be curious to see what relation can be established between the art and the age that produced it.  If my second hypothesis—­that art is the expression of an emotion for ultimate reality—­be correct, the relation between art and its age will