The painter David Levine once said, "There's nothing new but what's been forgotten." Paul Simon sang, "The world is old..." A lot of time has passed since the glaciers receded and many good ideas have been forgotten. A few of those good ideas can be found in used bookstores.
Years ago I found a copy of Sir Joshua Reynolds' Discourses on Art, delivered as a series of lectures to students at the Royal Academy in London between 1768 and 1792. Reynolds' thought and rhetoric has an almost impenetrable 18th century air about it, but hiding there among the flourishes are wonderful gems of advice. In Discourse XI Reynolds addresses the issue of "finish" and the relationship of the parts of a painting to the whole; in other words, composition.
For an abstract of the essential points of Discourse XI, go to my recent post on Painting OWU, my blog for painting students at Ohio Wesleyan.