Inevitably, in view of these new techniques, the art of harmony evolved rapidly at this time. Whereas Renaissance music had still used the medieval modes, although with important modifications, Baroque musicians developed the modern major/minor system, which we discussed on pages 31–33. Chords became standardized, and the sense of tonality — the feeling of centrality around a tonic or home pitch — grew much stronger.

Composers also developed a new way of handling the chords so that their interrelation was felt to be more logical or coherent. Each chord now assumed a special role, or function, in relation to the tonic chord (the chord on the home pitch). Thus when one chord follows another in Baroque music, it does so in a newly predictable and purposeful way. Functional harmony, in this sense, could also be used as a way of organizing large-scale pieces of music, as we will see later.

In a Baroque composition, as compared with one from the Renaissance, the chords seem to be going where we expect them to — and we feel they are determining the sense or the direction of the piece as a whole. Harmonies no longer seem to wander, detour, hesitate, or evaporate. With the introduction of the important resource of functional harmony, Baroque music brings us firmly to the familiar, to the threshold of modern music.