Vergil,
Aeneid 1.209:
spem voltu simulat, premit altum corde dolorem.
In John Dryden's translation this becomes:
His outward smiles concealed his inward smart.
Dryden also echoes this line in
Annus Mirabilis 73:
His face spake hope, while deep his sorrows flow.
James Mountford,
Latin Prose Composition (aka
Bradley's Arnold), in the
General Vocabulary, s.v.
pretend, says:
Simulo = I pretend something exists which does not; dissimulo = I try to conceal something which does exist.
Aeneas simulates hope (
spes) and dissimulates sorrow (
dolor). Those afflicted by melancholy wear the mask of Aeneas every day.