A concord of sounds, several tones of different pitch sounded as a chord; among the Greeks, the general term for music. Although it is probable that the notion and practice of harmony existed among the peoples of the North - the Scandinavians, Celts, and Britons - and that singing in two or more parts was in popular use much earlier, the principle was not applied to the chant of the Church, as far as we now know, until the ninth century. The first interval which was used simultaneously with the melodic note was the fourth below (See Counterpoint). By doubling this interval in its upper octave, the interval of the fifth above the melodic note was formed, thus suggesting three-part harmony, which was introduced into practice later on. It was Hucbald de St-Amand (840-930) who systematized and gave a theoretic basis to this manner of performing the music of the Church (Organum). These added intervals were conceived as ornaments to the liturgical melody, and moved in parallel motion with it. The text syllables were applied to them in the same manner as they were to the original melody. When, in the eleventh century, one or more added (or organal) voices were beginning to be sung in contrary motion to that of the original melody, they would begin on the initial note of the melody, on its octave or on the fifth above, and at the end of the organum, or piece of music, return to their starting point, thus forming a final point of repose, consonance, or harmony. While, up to the twelfth century, the concept of harmony was restricted on the Continent to the simultaneous sounding of the intervals of the fourth below the melodic note with its octave above, in the British Isles - in their gymel (cantus gemellus) - they were using also the interval of the third both below and above the melodic note, and, by transposing the third below an octave higher, they created the so-called falso-bordone, faux-bourdon, false bass, or three-part harmony (inverted triad), as we know it to-day.

The interval of the third was not definitely recognized as a consonance, however, until the end of the fifteenth century. With the introduction in France, in the twelfth century, of the déchant (discantus), which consisted at first in the addition of one freely improvised melody to the cantus firmus, but which was soon increased to two or three, the idea of harmony made a further great advance. Contrary motion and rhythmical differentiation of the voices, as against the parallel motion and equal notes in all voices of the organum, gymel, and falso-bordone, now became the general practice, and the necessity arose of formulating rules governing the incipiency, movement, and return to the point of rest or consonance of the different voices of the composition. Thus the laws of counterpoint and a system of notation fixing the exact time-value of each note (mensuralism) came into existence. The necessity felt in music as in the other arts during the thirteenth and fourteenth centuries for greater expansion and freer expression originated, developed, and perfected many new forms. Among these was the conductus, a composition in four-part harmony, the principal part being sung and the others generally played on instruments. Another form of composition, the motetus (prototype of our present day motet) consisting of a Gregorian theme with two or more added original melodies, the latter sometimes having differing texts, originated at the beginning of the thirteenth century. The motetus meant a considerable step toward the independence of the various voices or parts.

Another very important move takes place at this time in the definitive discarding of the practice of having the intervals of the fifth and octave move in parallel motion (Johannes de Muris, Normannus). With the striving for independence of the voices or parts goes hand in hand the desire for consonance (harmony) on the strong notes of the cantus firmus, even in the many secular forms which came into vogue at this period, e. g., caccia (chase), rondeau (round dance), until we have the perfected canon (first Netherland school), in which the various voices move with the greatest possible rhythmical variety without detriment to symmetry and meet in perfect consonance on the thetic tones of the cantus firmus. From now until the beginning of the seventeenth century, we witness the production of works (Roman school, Palestrina) in which the concept of harmony, or harmonious co-operation of many different parts, is more luminously exemplified than it has been at any time in the history of music. It must be borne in mind that up to this time the liturgical melody, based upon the diatonic scale, still dominated every field of musical creation, but especially the compositions destined to serve the Church. The melody, vehicle of the liturgical word, was the all-important factor and informing principle of the whole structure. Hence the compositions to liturgical texts of those days may be defined as a number of melodies giving expression to the text and harmonizing among themselves. Their flow is untrammelled and unrestrained, and harmony among them results from their flow incidentally. The diatonic character of the melodies or voices, vehicles and servants of the sacred text, imparts and preserves to the whole structure the elevation, serenity, nobility, objectivity, and universality, which characterize the works of the masters of this period. The temporary dissonances resulting from passing notes, suspensions, etc., are constantly being resolved into consonance (harmony, repose, peace), with which the composition also invariably ends. We have here a true image of the Christian's life with its constant change from sorrow to joy, its unceasing combat in working out its ultimate salvation. As the diatonic character of each voice is kept intact, except when chromatic alteration is necessary as a concession to harmony, the hearer never loses consciousness of the fact that the melodic (moving) principle is paramount, and that harmony (repose) is only a temporary result which he may enjoy but not permanently dwell upon.

The endeavour to throw off the supremacy of the liturgical melody with its diatonic character (which was then and is now the expression in music of the spirit of the Church par excellence), and to substitute for it a system better adapted to the expression of individual thought and feeling, began as early as the first part of the thirteenth century. It became known by the general name of ars nova. In the numerous instrumental and secular vocal forms which were developed at this time and later (ricercar, canzone, tiento, toccata, præambulum, capriccio, chanson, strambotto, madrigal), original melodies were often substituted for a cantus flrmus taken from the Gregorian chant. The harmonic element gradually gained ascendancy over the melodic in the whole field of production, and exercised an ever-growing influence over the general taste. It was through the Venetian school, founded by Adrian Willaert (1480 or 1490-1562) and continued principally by the two Gabrielis, Andrea and Giovanni, that this trend was applied to the music of the Church.

The custom introduced by Willaert, and imitated by many other masters of the time, of writing and performing works for two or more choruses, which would alternate and occasionally unite in brilliant harmonic climaxes, met with such general approval that it spread over all Italy, invaded Rome itself, and soon overshadowed the melodic or truly polyphonic form, so that it hastened the complete emancipation from the melodic principle as exemplified in the Roman school. With the Venetian masters the harmonic effect had become the chief aim instead of being a result incidental to the melodic co-operation of the parts. But this school enjoyed only a passing favour. It was only a reflex of a departing glory, the effect of a cause which had been removed. In the meantime, Gregorian chant, now poorly performed at best, gradually fell into almost complete disuse. The humanists, having lost the spirit of which it is the expression, decried it as inadequate, unsatisfactory, even barbarous, and advocated a return to Greek monody. In imitation of this, metrical poems were set to music for one voice with other voices or instruments as harmonic adjuncts. They insisted upon a style capable of expressing every individual feeling and every subjective state of the soul. In their writings they gave a philosophic basis for that which musicians had been practising more or less for generations, but which now gained supremacy. With Gioseffo Zarlino's (1517-1519) definition and introduction into practice of the dual nature of harmony, major and minor, a further step was made in the breach with the past.

The diatonic modes were now definitively replaced by the two modern tonalities, the major and minor keys. Composers no longer conceived their creations melodically but harmonically. The thoughts and emotions, suggested and engendered by the sacred text and expressed in the diatonic melody, yielded to the subjective psychic state, harmonically expressed, of the composer. Introspection took the place of contemplation. The concept of harmony was no longer limited to the consonance as formerly understood. The chromatic scale and chords built out of its elements found their way into use, and, with the introduction of the chord of the seventh (consisting of the tonic, third, fifth and seventh intervals of the scale) by Claudio Monteverdi (1567-1643) and the same master's further innovation of setting liturgical texts to what became known as the aria and the arioso forms, the abandonment of the former standard was complete. Secular forms, the oratorio, the opera, and purely instrumental music, now began that conquest of the mind and heart of man which we have witnessed since. This conquest was so rapid that as early as the end of the seventeenth century and for the next two hundred years the style in which even the greatest masters wrote for the Church was identical with that in which their secular works (operas, oratorios, symphonies) were composed. The beginning of the nineteenth century witnessed the last stage of the degradation of church music. Every form of subjective feeling found its way into the temple by means of music. Not only were comparatively few works to be heard anywhere which were expressive of the spirit of the liturgy, but even from the standpoint of art music written to liturgical texts had, with rare exceptions, fallen below the level of that composed for the theatre and concert hall. Gregorian chant was either entirely ignored or performed in a wretched manner. Being dominated by the spirit of the world, as expressed through the multiform voice of secular music, men had no longer any affinity with, or taste for, the simple diatonic chant.

A great change has taken place within the last fifty years. Three successive popes have urged and commanded the restoration of the chant of the Church to its rightful place. Learned men have made the Catholic world acquainted with its nature, form and spirit. Model performances of the chant in many places throughout the world have revealed to the faithful its beauty and revived a taste for it. The restoration of the chant signifies the restoration of the objective standard as against the subjective. Not only has the chant come into its own again, but, through the mighty labours of men animated by the spirit of the Church, the great productions of polyphony have been made accessible so that the present generation is enabled to study the harmonic structures which were reared upon the diatonic modes in the fifteenth, sixteenth and seventeenth centuries. Within the last fifty years the diatonic modes have again become the basis for many works of polyphony which may be placed side by side with what is highest and best in the great period of the art. The musical world to-day presents a striking illustration of the present moral and mental state of mankind. The principle of cultivating harmony as an end in itself, rather than seeing in it the incidental result of harmonious co-operation of many independent voices, has borne its full fruit. The extreme modern development of secular music is but the legitimate offspring of the revolt against the diatonic principle; which revolt was the musical expression of the spirit of the Renaissance. Its strident and cacophonous dissonances are but the manifestation of modern moral and social disorder. In its luxuriant harmonic combinations modern sensuality finds its outlet and indulgence. Opposed to this, as expressive of the spirit of the Church, we have restored to its rightful supremacy as servant of the liturgical word, the diatonic melody, which in its turn, is served by harmony.

WOOLDRIDGE, Oxford History of Music (Oxford, 1901); COUSSEMAKER, Histoire de l'harmonie au moyen-âge (Paris, 1852); RIEMANN, Geschichte der Musiktheorie (Leipzig, 1898); JACOB, Die Kunst im Dienste der Kirche (Landshut, 1885).

JOSEPH OTTEN.