Pulitzer Prize winning writer and author Jon Franklin on the writer as a 'trained observer':
"...I consider learning to observe, that is to _see_, to be a vision issue. It requires the devotion and focus found, for example, in good priests, and it is the single most precious thing we offer our readers..."
The more I think about this, the more I think Franklin has identified something very important about writing. I don't think I've ever heard anyone else identify this so clearly. The heart of good writing, both nonfiction and fiction, is keenly observed details.