I have often found it beneficial to sketch furniture while examining it. Unlike a photograph, a pencil insists a form be understood to be reproduced. But my sketches don’t always look like my subjects. My failing can be attributed to both my lack of skill and lack of understanding of the subject. I’m not convinced there’s a great deal I can do about the former, but I’m not all busted up about it. The latter, however, is the point here.
When we draw, we deconstruct what we see into tiny sub-elements of shape and color. We can never perfectly reproduce what we see. Always our work is an approximation of reality. For the uninitiated, the well spring is always the subject alone. Serious students drink in the subject, but also rely on things they know to be true or suspect may be true. This is why the old masters (extending that category into the early 20th century painters like Thomas Eakins) dissected cadavers.