In a letter to Durand dated January 7, 1913, Debussy stated that a piece inspired by "Toomai of the Elephants", a story from Rudyard Kipling's The Jungle Book, was not progressing, and that he would prepare an alternative piece. This alternative piece is believed to be Tierces alternées (Alternating Thirds). Following an introduction, the main motif appears in measures 11-14, succeeded by a tremolo passage of third chords played by alternating hands. Meanwhile, in the middle section, while the alternation of third chords is maintained, the character becomes sweet and graceful (measures 91-115) (see musical example). In its requirement to draw diverse timbres from consistent passage work, it shares characteristics with the Études written in 1915.

Musical Example: Beginning of the Middle Section, Measures 91-94