The Franco-Polish pianist has penned a five-bar quote for piano, which he has identified as a fugue from one of his own works.

Mortier de Fontaine enjoyed a fine reputation on the Continent as a pianist of technical ability. He was known especially in Germany for his performances of the Beethoven sonatas, particularly the late ones, and is said to have been the first to publicly perform the "Hammerklavier" Sonata, op. 106.