A song without words is a kind of gender of instrumental music — which may be adapted or inspired by a vocal song with words — but whose motives and phrases are built using pure music constructive patterns. Instrumental songs (IS) differ from songs whose music is set to words in that the musical phrases of the first express ineffable meaning and World-independent thoughts: Musical motives -- the building block of music language -- do not describe properties of objects that live in the World, but are part of sequences and phrases that refer to abstract relations. The meaning of phrases of IS is interpreted in the interface that relates musical expressions to abstract thought and passions (Descartes, Les passions de l'âme, 1649).
The origin of IS gender can be traced back to instrumental compositions in a style adapted from late 15th century "carmina" ('canti', It), which were written using a pure music language in an ornamented and imitative style (i.e.: Johannes Ghiselin’s “La Alfonsina”, printed in Petrucci’s Odhecaton; Josquin des Prez’s “La Bernardina”, printed in Petrucci’s Canti C).