Middle Ages music scholars were confronted with two distinct traditions. That of the Church’s liturgical chant, the origins of which are not entirely known, and that of Greek harmonics, which was purely theoretical in nature. The two traditions merged in the 9th century during the Carolingian revival. This marked the birth of modern Western music. The centuries that followed saw some fairly significant changes, but the original core remained. The purely diatonic music of the early Middle Ages was enriched with chromaticism, and new consonances such as thirds and sixths, major and minor, were accepted in addition to the fourths and fifths used until then. In this way, Pythagorean intonation was surpassed, leading to the so-called just intonation. The adoption of this richer intonation, however, brought with it a number of disadvantages that were resolved with the introduction of temperament. Monody was flanked by polyphony, which then became counterpoint, in which different melodic lines intersected in a very complex way; finally, there was a reaction to this complexity and a return to Greek music, in which more attention was paid to the text: thus opera was born.