This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
In form drawing the chief aim, as the name implies, is to express form and not color and texture. In order to do this, shadows and cast shadows are indicated only as far as they help to express the shape. This is the kind of drawing practiced by most of the early Italian masters, and it has been called the Florentine method. It is often a matter of careful outline with just enough shadow included to give a correct general impression of the object. There is usually little variety in the shadow and no subtle graduations of tone, but the shadows are indicated with sufficient exactness of shape to describe the form clearly. Form drawing is a method of recording the principal facts of form with rapidity and ease and of necessity deals only with large general truths. Perhaps its most distinguishing feature is that it does not attempt to suggest the color of the form.