Guillaume de Machaut’s Rondeau 14, from the 14th century, is a crab canon over a palindrome: When the singers reach the end of the line, the tenor (the lowest voice) reverses course and reads his music backward, and the other two voices follow suit, exchanging parts.

So they arrive where they started. De Machaut titled the piece “Ma fin est mon commencement” — “In my end is my beginning.”