The Birth of Venus Dorotheus". Pliny also noted a second painting by Apelles of Venus "superior even to his earlier one," that had been begun by artist but left unfinished. The Roman images in various media showing the new-born Venus in a giant shell may well be crude derivative versions of these paintings. Botticelli could not have seen the frescos unearthed later in Pompeii, but may well have seen small versions of the motif in terracotta or engraved gems. The "House of Venus" in Pompeii has a life-size fresco of Venus lying in the shell, also seen in other works; in most other images
Sandro Botticelli without describing it, an altarpiece by Botticelli for the Convertite, an institution for ex-prostitutes, and various surviving unprovenanced works were proposed as candidates. It is now generally accepted that a painting in the Courtauld Gallery in London is the "Pala delle Convertite", dating to about 1491–93. Its subject, unusual for an altarpiece, is the Holy Trinity, with Christ on the cross, supported from behind by God the Father. Angels surround the Trinity, which is flanked by two saints, with Tobias and the Angel on a far smaller scale right in the foreground. This was probably a votive addition, perhaps requested