Mass

/mas/, n.

1. the celebration of the Eucharist. Cf. High Mass, Low Mass.

2. (sometimes l.c.) a musical setting of certain parts of this service, as the Kyrie eleison, Gloria, Credo, Sanctus, Benedictus, and Agnus Dei.

[bef. 900; ME masse, OE maesse < VL *messa, LL missa, formally fem. of L missus, ptp. of mittere to send, dismiss; perh. extracted from a phrase in the service with missa est and a fem. subject]

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I

Celebration of the Eucharist in the Roman Catholic church.

It is considered a sacramental reenactment of the death and resurrection of Jesus as well as a true sacrifice in which the body and blood of Jesus (the bread and wine) are offered to God. It is also seen as a sacred meal that unifies and nourishes the community of believers. The mass includes readings from Scripture, a sermon, an offertory, a eucharistic prayer, and communion. The rite was greatly changed after the Second Vatican Council, notably in the adoption of vernacular languages in place of Latin. See also sacrament, transubstantiation.

II

Quantitative measure of inertia, or the resistance of a body to a change in motion.

The greater the mass, the smaller is the change produced by an applied force. Unlike weight, the mass of an object remains constant regardless of its location. Thus, as a satellite moves away from the gravitational pull of the Earth, its weight decreases but its mass remains the same. In ordinary, classical chemical reactions, mass can be neither created nor destroyed. The sum of the masses of the reactants is always equal to the sum of the masses of the products. For example, the mass of wood and oxygen that disappears in combustion is equal to the mass of water vapour, carbon dioxide, smoke, and ash that appears. However, Albert Einstein's special theory of relativity shows that mass and energy are equivalent, so mass can be converted into energy and vice versa. Mass is converted into energy in nuclear fusion and nuclear fission. In these instances, conservation of mass is seen as a special case of a more general conservation of mass-energy. See also critical mass.

III

(as used in expressions)

air mass

critical mass

Einstein's mass energy relation

mass action law of

mass flow

mass movement

mass wasting

mass production

mass spectrometry

mass spectroscopy

mass transit

requiem mass

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▪ Roman Catholicism

      the celebration of the Eucharist (q.v.) in the Roman Catholic church. The term mass is derived from the rite's Latin formula of dismissal, Ite, missa est (“Go, it is ended”). According to Roman Catholic teaching, the mass is a memorial in which the death and Resurrection of Jesus Christ are sacramentally reenacted; it is a true sacrifice in which the body and blood of Jesus, under the appearances of bread and wine, are offered to God; and it is a sacred meal in which the community symbolically expresses its unity and its dependence upon God and seeks nourishment in its attempt to bring the gospel message to all men. The mass consists of two parts: the liturgy of the Word, which includes readings from Scripture and the homily (sermon), and the liturgy of the Eucharist, which includes the offertory, the eucharistic prayer (canon), and the communion. The rite was changed greatly after the second Vatican Council (Vatican Council, Second) (1962–65), most conspicuously in the use of vernacular languages in place of the traditional Latin.

▪ music

      in music, the setting, either polyphonic or in plainchant, of the liturgy of the Eucharist. The term most commonly refers to the mass of the Roman Catholic church, whose Western traditions used texts in Latin from about the 4th century to 1966, when the use of the vernacular was mandated. The Anglican (Anglicanism) mass, commonly called communion service, contains the same elements but has usually been sung in the English translation from the Book of Common Prayer. The Lutheran mass consists of the first two elements of the Roman mass, the Kyrie and the Gloria. In modern times other Protestant churches have borrowed freely from musical masses for their own liturgical uses and for special music. (For the Eastern traditions see Byzantine chant; Armenian chant; Ethiopian chant; Coptic chant; Syrian chant.)

      The Ordinary. The Ordinary of the mass employs texts that remain the same for every mass. Those sung by the choir are, in the Latin mass, the Kyrie, Gloria, Credo, Sanctus (sometimes divided into Sanctus and Benedictus), and Agnus Dei, although the intonations of Gloria and Credo are sung by the celebrant.

      The earliest musical settings of the mass were plainchant (one voice part, in free rhythm) melodies. From the 9th to the 16th centuries some plainchants were expanded by means of tropes; i.e., the grafting of new music and new texts onto the original chants.

       organum, the simultaneous combination of more than one melody, was developed in about the 9th century. The Winchester Troper, a manuscript from about the 11th century, contains 12 Kyries and 8 Glorias in two-part organum; the notation, however, cannot be deciphered. In the 12th and 13th centuries further developments of organum took place in the Magnum Liber Organi.

      In about 1300, polyphonic cycles of the Ordinary (having two or more sections musically related to one another) appeared. The French composer Guillaume de Machaut (Machaut, Guillaume de) (d. 1377) wrote the first complete Ordinary cycle, the Messe de Notre Dame.

      The secular music style of the 14th century manifested itself in Ordinary settings, which at that time were rarely based on plainsong melodies. The music is basically in descant or treble-dominated style: a melodically and rhythmically elaborated upper part over two slower moving parts, usually for instruments.

      In the 15th and 16th centuries numerous composers chose the Ordinary as a chief means of musical expression. Masters of the 15th century were the Englishman John Dunstable (Dunstable, John) and the Burgundian Guillaume Dufay (Dufay, Guillaume). Both applied the treble-dominated style of plainsong. Dufay brought to completion the developments of cantus firmus mass, in which each section of the Ordinary is based on a precomposed melody, or cantus firmus (q.v.), usually either a plainchant melody or a secular song. The celebrated Flemish composer Josquin des Prez (d. 1521), among his several other innovations, perfected the parody mass: the borrowing and free elaboration of two or more parts of another sacred or secular composition within a new setting of the Ordinary texts. He also standardized the use of melodic imitation by having each voice begin in turn with the same motif.

      The works of the Italian composer Giovanni da Palestrina (d. 1594) summarize the techniques of his era. His style was later termed the stile antico, the ancient polyphonic style, in contrast to the stile moderno, the 17th-century modern solo style. In the 17th century these two styles are found, sometimes even juxtaposed, in the Ordinary of the mass settings, along with the use of the concertato principle: one or more solo voices or instruments, in running scale passages, that contrast with the whole choral and instrumental ensemble. In such settings the text is separated into smaller units to permit varied settings and instrumental interludes.

      In the 18th century, the Neapolitan Alessandro Scarlatti (Scarlatti, Alessandro) continued the operatic approach, as did Haydn and Mozart. Beethoven's Missa Solemnis (completed 1823) flows from the contemplation of the liturgy, as does J.S. Bach's Mass in B Minor (1724–46), but neither was meant to accompany it.

      Near the beginning of the 19th century in Germany there arose a renewed interest in plainchant and 16th-century polyphony, ideals that in 1868 initiated the Cecilian movement for reform in Roman Catholic liturgical music. But composers still wrote settings for orchestra, chorus, and soloists, notable examples being Franz Liszt, Charles-François Gounod, and Anton Bruckner.

      In 20th-century style are the Ordinary settings of Igor Stravinsky, the Hungarian Zoltán Kodály, the French composer Francis Poulenc, and the British composers Ralph Vaughan Williams, Benjamin Britten, and William Walton. A kind of troped Ordinary is the American Leonard Bernstein's Mass.

      The Proper. The Proper of the mass includes the scriptural texts that change daily with the liturgical calendar. The Proper texts sung by the choir, with the participation of soloists, are the Introit, Gradual, Alleluia or Tract, Sequence, Offertory, and Communion.

      As with the Ordinary, the earliest settings are in plainchant, and troping also existed in the Propers. The Winchester Troper includes 3 Introits, 53 Alleluias, 19 Tracts, and 7 Sequences in undecipherable note-against-note organum. Around 1200, two of the composers of Notre-Dame Cathedral, Paris, Léonin and Pérotin, wrote the Magnus Liber Organi, a compilation including settings of 59 Graduals and Alleluias in two to four voices. Some pieces have an unmeasured melismatic (many notes per syllable) upper voice over prolonged notes of the chant; others have measured, regular, recurring rhythmic patterns in all of the voices.

      Around 1430 Dufay reawakened interest in settings of the Proper. Much later, collections of polyphonic Proper settings for the liturgical year are found in the German Heinrich Isaac's Choralis Constantinus (begun 1550, completed 1555 by Ludwig Senfl) and in the German Georg Rhau's publications for the Lutheran Church in 1539 and 1545.

      Within the Roman Catholic Church, the liturgical reforms of the Council of Trent (1545–63) gave new impetus to Proper settings. Starting with Giovanni Contino in 1560, numerous Italian composers wrote settings of the Proper. In 1605 and 1607 appeared the two books of the English composer William Byrd's Gradualia, a collection of polyphonic Propers for major feasts.

      Systematic development of the Propers in music was rare from the Baroque era on.

▪ physics

      in physics, quantitative measure of inertia, a fundamental property of all matter. It is, in effect, the resistance that a body of matter offers to a change in its speed or position upon the application of a force. The greater the mass of a body, the smaller the change produced by an applied force. By international agreement the standard unit of mass, with which the masses of all other objects are compared, is a platinum-iridium cylinder of one kilogram. This unit is commonly called the International Prototype Kilogram and is kept at the International Bureau of Weights and Measures in Sèvres, France. In countries that continue to favour the English system of measurement over the International System of Units (SI), the unit of mass is the slug, a mass whose weight at sea level is 32.17 pounds.

       weight, though related to mass, nonetheless differs from the latter. Weight essentially constitutes the force exerted on matter by the gravitational attraction of the Earth, and so it varies from place to place. In contrast, mass remains constant regardless of its location under ordinary circumstances. A satellite launched into space, for example, weighs increasingly less the further it travels away from the Earth. Its mass, however, stays the same.

      According to the principle of conservation of mass (mass, conservation of), the mass of an object or collection of objects never changes, no matter how the constituent parts rearrange themselves. If a body split into pieces, the mass divides with the pieces, so that the sum of the masses of the individual pieces is equal to the original mass. Or, if particles are joined together, the mass of the composite is equal to the sum of the masses of the constituent particles. However, this principle is not always correct.

      With the advent of the special theory of relativity by Einstein in 1905, the notion of mass underwent a radical revision. Mass lost its absoluteness. The mass of an object was seen to be equivalent to energy, to be interconvertible with energy, and to increase significantly at exceedingly high speeds near that of light (about 3 × 10⁸ metres per second, or 186,000 miles per second). The total energy of an object was understood to comprise its rest mass as well as its increase of mass caused by high speed. The rest mass of an atomic nucleus was discovered to be measurably smaller than the sum of the rest masses of its constituent neutrons and protons. Mass was no longer considered constant, or unchangeable. In both chemical and nuclear reactions, some conversion between mass and energy occurs, so that the products generally have smaller or greater mass than the reactants. The difference in mass is so slight for ordinary chemical reactions that mass conservation may be invoked as a practical principle for predicting the mass of products. Mass conservation is invalid, however, for the behaviour of masses actively involved in nuclear reactors, in particle accelerators, and in the thermonuclear reactions in the Sun and stars. The new conservation principle is the conservation of mass-energy. See also energy, conservation of; energy; Einstein's mass-energy relation.

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