Claus Sluter (c. 1360-1406) is now celebrated as the Netherlandish sculptor who introduced both "naturalism" and "compassion" into post-medieval art. Focusing on his Tomb of Philip the Bold (mostly executed between 1404 and 1406), this study examines a particular motif: Sluter's "pleurants", or grief-stricken mourners with veiled faces. In this case, the motif - originally called "Tristia velata" - is shown to have been a commonplace in classical-era texts, so revealing the "humanistic" sources of Sluter's art. The "veiled grief" topos is also traced in Renaissance texts based on the same classical-literary legacy.