Sometimes my use of the term "purchase" draws blank looks. I often use the term in its mechanical sense to describe an advantageous hold or position on something. Most often this term comes up when rigging with line. A successful rigging job involves optimizing the mechanical advantage available to exert a force on an object. Purchase happens at every point where there is a change in forces being applied, a requirement for friction, bearing, traction, etc.

Yesterday I was struggling with a design for a residential remodel project. I was repeatedly turning out concepts without attaining the level of satisfaction that allows me to develop a design. A concept has to provide promise on many levels to prove worthy of graphic development beyond sketches. There is a very satisfying moment when I feel that I've gained purchase in a design problem; the point when I feel there is sufficient engagement that I know the concept may well withstand the test of a scaled drawing and still preserve the design intent. The problem is far from solved at that point, but the advantage is present and I can proceed with the rigor and scrutiny of measured drawings.