Weinberg chooses the perfect metaphor to describe his writing style and a way all of us can develop the opportunity to write something people will want to read. The fieldstone method is actually taken from a style of construction. A fieldstone is literally a stone you find in a farm field. For centuries, people have collected these rocks and used them to build walls, fences and buildings. It is impossible to understate how complex a task this is. Three decades ago I owned an acreage and decided to build a small fireplace in my yard. I went to the local creek and picked up many smooth and very hard rocks and got to work. I spent hours mentally rearranging the rocks so that something resembling a wall could be built. Given that most of the rocks were metamorphic, trimming them to fit was generally not an option. However, once you find the niche for each of the rocks, a wall can be built and you can stand back and be quite rightly impressed with yourself.
Writing a book is like that, single words cannot be trimmed to suit and the best word surrounded by the wrong words is an ugly creature. Each word must be surrounded with just the right context and when it works, you have something of merit that will last a long time. To Weinberg, his fieldstones are ideas, or more precisely snippets of ideas. A short phrase, an unusual word, an idea in or out of context or an (in)advertent word play are all stones to record and catalog. He also is also quite right in stating the fundamental rule of being a writer, "Write about something you believe in!" Which not unexpectedly, is a good rule for anything you do.
The good writer, like nearly all-successful and creative people, must be able to do two things:
Bookreview by Charles Ashbacher: "Weinberg on Writing: The Fieldstone Method", in Journal of Object Technology, vol. 8, no. 2, March - April, pp 93-94 http://www.jot.fm/books/review26/