Where Have All the Rainbows Gone?
The trouble which faces all artists these days, is that there are only a certain number of combinations of things that the human mind can find beautiful: our minds are finite masses. As a result, the more we know, the less total possible beauty exists for us to experience. As such, innocence seems more beautiful to us than experience (for example, as a child, when almost all experience is, as yet, unknown, there exists a great many beautiful feelings to be had.) After already having them, they are not of the same quality as they once were, and so, the older we become, the less interesting the world becomes as well.
More importantly, on the scale of cultural experience, the more knowledgeable our society becomes, the less we will be able to discover of new beauties over time. There are only a limited number of methods in which paint may be applied onto a two-dimensional surface. Artists today are finding it more and more difficult to create new wonders (for they have already been mostly done!) I am not saying that the solution is to return to innocence, but that we must make more strident efforts to find the new experiences that may still be uncovered. Some knowledge is even required in order to have certain beautiful experiences (e.g., mathematical algorithms or sophisticated literature.)
Therefore the more we know, the more we need great artists to provide new experiences, and the more difficult it becomes for these artists to achieve this goal. Where have all the rainbows gone? They were lost in the sea of knowledge as they faded from our imaginations and we began understand them.