Anonymous, "Viderunt omnes"(11th century) Mahler, Symphony 1, first movement, mm 1-13 (1888-1899)

Both of these pieces did not have a set rhythm. The chant, of course, is not supposed to have a set rhythm, but the other piece should. Maybe this was the case because I did not hear the rest of the fifth piece; although I am pretty positive that I understood where the piece was going after listening to just a short section.