It is the lines made by unnecessary strain to which I refer.
Strange to say the unquiet faces come mostly from shallow feeling.
Usually the deeper the feeling the less strain there is on the face.

A face may look troubled, it may be full of pain, without a touch of that strain which comes from shallow worry or excitement.
The strained expression takes character out of the face, it weakens it, and certainly it detracts greatly from whatever natural beauty there may have been to begin with.

The expression which comes from pain or any suffering well borne gives character to the face and adds to its real beauty as well as its strength.
To remove the strained expression we must remove the strain behind; therefore the hardest work we have to do is below the surface.

The surface work is comparatively easy.
I know a woman whose face is quiet and placid.

The lines are really beautiful, but they are always the same.