there are men whose laugh is as untrue as anything about them; who cannot laugh.
 Thomas Carlyle, On Heroes, Hero-Worship, and The Heroic in History (1841). copy citation

Context

“Through life we find him to have been regarded as an altogether solid, brotherly, genuine man. A serious, sincere character; yet amiable, cordial, companionable, jocose even;—a good laugh in him withal: there are men whose laugh is as untrue as anything about them; who cannot laugh. One hears of Mahomet's beauty: his fine sagacious honest face, brown florid complexion, beaming black eyes;—I somehow like too that vein on the brow, which swelled up black when he was in anger: like the "horseshoe vein"” source