The "Cryptograms" No. 1 and 2 (DLT0250) are suites written for organ and flute, the 3rd (DLT0251) is for organ and viola. The title of these pieces comes from a sort of pun: The Temple of the Marais where Jean-François Laffay was organist, was one of the first places of worship given to Protestants by Napoleon 1st. The Temple was built by François Mansart in 1633. Under the nave is a "crypt" in which Jean-François Laffay gave little concerts held monthly.
He composed these suites in the form of sonatas with 3 or 4 movements to be played during the concert and gave them the name of ... cryptograms!