The article proves that the three-part motet “Qui secuntur” also belongs to the earliest isorhythmic motets placed among the musical interpolations in “Roman de Fauvel” (c. 1317). This is evidenced by isorhythm in the tenor, noted by researchers, and iso­periodic in the parts above the tenor, identified by the article’s author. The motet shows several common features with another isorhythmic motet of the musi­cal collection—“In nova fert”, attributed to Philippe de Vitry. First of all, this is a change of modus in talea, used for the first time in these two motets, which is con­veyed in the motet “Qui secuntur” by the Ars antiqua notation (according to Franco of Cologne), which prevented researchers from noticing it. The subordination of can­tus prius factus in the tenor of the motet “Qui secuntur” to the number “seven” and the presence of two different modes in talea are interpreted as semantic projections onto the music of the meanings contained in motet texts.