For Barfield (and the idea is of course not original with him), photography changed the nature of art:

The advent of the photograph did something which could hardly have been anticipated by those who invented it, though it may well be that it would not have worried about them if it had. It all took a little time, but one thing that the photograph did was to kill stone dead (well not quite stone dead, for the wound has only proved mortal in our own time) just that leading principle of aesthetic theory, that principle of art, which had held sway at least from the time of Aristotle down to the eighteenth century, the theory that the function of the artist is to imitate nature. The imitation of nature, now that it was being done by applying the sweet rules of perspective, had become altogether too easy; so easy that you could make a little gimmick that would do it all for you. (RM 71)