Institutio Oratoria

But they must never he fixed or protruding, languid or sluggish, lifeless, lascivious, restless, nor swim with a moist voluptuous glance, nor look aslant nor leer in amorous fashion, nor yet must they seem to promise or ask a boon. As for keeping them fully or partially closed while speaking, surely none save an uneducated man or a fool would dream of doing such a thing.

And in addition to all these forms of expression, the upper and lower eyelids can render service in support of the eyes.