valeur ajoutée

Added value — the addition of a short duration (a dot, an extra note, or a short rest) that disrupts an otherwise regular rhythmic pattern, creating asymmetry and preventing mechanical repetition. One of Messiaen's core compositional techniques.

Look for the dot or short note that extends a rhythm by one small unit. Respect it precisely — rushing through added values destroys the intended asymmetry that animates Messiaen's rhythmic language.