It is like a doll face that is, perhaps, perfect in detail, but utterly devoid of expression.
The artist who paints a portrait is a failure without the ability to give expression: hence in architecture the acute-angled spires or arched roofs have the same expression that the “long face” carries.
If we smile, the mouth curves upward; if we grieve, the lines turn downward.
108. In festival decorations, joy is expressed by loops, curves and festoons.
109. In serious decorations (libraries, studies, church or office work) straight lines are used; curtains are gathered in plaits so that the sags and drapes are all out of them; they are drawn. It is the same when we say of a person: “He looks serious, his face is drawn; it is full of lines.”
110. The observation, “a broad smile on his face,” means literally just that; the lines extend outward and upward, giving an expression of breadth and joy to the countenance.
ILLUSION