Greg Martin just released his "Capturing Heaven" article, which has been quite some time in the making.  His description is as good as any I could provide, so here it is:

"An article detailing the basic elements of space and how they relate to art, Capturing Heaven has been a project I've been struggling to complete for the last two years. Now it is finally finished and available to the public, for the betterment of all. Over 4,400 words long and image-packed with the best true-life or artistic examples I could find, this article is aimed to help people better understand space and get that essential intuitive understanding that great art stems from."

This is in PDF format and weighs-in at 14.4 mb.  It is being hosted over at DeviantArt.  We talk often around here about the importance of understanding this subject and being able to produce accurate results when desired.  This article goes a long way in delving into these ideas.  It is a very good read.  Take a look via THIS LINK.