Jean-Baptiste Greuze was a famous French painter of the later 18th century. A very well-received genre and portrait painter, he was less successful at the more prestigious field of history painting, which he desperately wanted to be remembered for. Although he died penniless due to profligacy and his wife's embezzlement of his money, his work as an artist was popular both during his lifetime and after his death.
Because of his popularity his paintings were highly valued: in 1865 his painting La Jeune Fille à l'agneau ("Young Girl with a Lamb") sold for one million two hundred thousand francs. His work was apparently liked by Professor James Moriarty, who kept a painting of a girl by Greuze above the desk in his office. Sherlock Holmes was able to use this fact, and the auction price of his Girl with a Lamb, to convince Inspector Alec MacDonald of Moriarty's criminal nature: on a professor's salary, Moriarty would never be able to afford such an exorbitantly-priced work, and must therefore have another, hidden source for his immense wealth.
- Strangely, Holmes does not consider the obvious idea that Moriarty simply stole the Greuze painting.
- The reference to La Jeune Fille à l'agneau, while literally meaning "Young Girl with a Lamb", may be taken as a pun meaning "The Young Girl from Agnew". This could be is a reference to the infamous 1876 theft of an immensely valuable portrait of Georgina, Duchess of Devonshire by Gainsborough, which was stolen from the art dealer William Agnew. The crime was not solved for twenty-five years, nor the painting recovered, until the Pinkterton Detective Agency managed to trace it back to the American master criminal Adam Worth, nicknamed the "Napoleon of Crime" and speculated to be the basis for Professor Moriarty. Because of a lack of evidence, Worth was not arrested, but eventually sold the painting back to Agnew for $25,000.