… the Suite (originally Symphony) in E (1903), in which distinctive Respighian phraseology is often foreshadowed. Here, as in Christus [composed at age 19], there are occasional signs that he was responsive to Gregorian chant long before he met his future wife, despite her oft-quoted claim that it was she who first induced him to study plainsong systematically.

Vetrate di chiesa, though it too is colourful and ostensibly pictorial, consists largely of orchestral amplifications of the abstract Tre preludi sopra melodie gregoriane for piano (1919–21).

The best known of the overtly abstract compositions whose use of plainsong-like material followed on from the Tre preludi is the Concerto gregoriano for violin and orchestra (1921), whose central movement features the familiar Easter sequence Victimae paschali. Elsewhere in the work the allusions to plainchant are more fleeting and disguised; the quasi-pastoral result parallels some of the more calmly modal music of Vaughan Williams. Likewise pervaded by freely plainsong-like themes are the long and rather diffuse Concerto in modo misolidio for piano and orchestra (1925), and the more impressive Quartetto dorico (1924), in which predominantly modal material is put to richly varied uses within a seemingly rhapsodic yet thematically unified single movement structure.

in Maria egiziaca – originally designed for small-scale, semi-staged presentation in the concert hall but thereafter performed quite often in Italian opera houses – he matched Guastalla’s self-consciously archaic libretto with austerely evocative music in which Gregorian, Renaissance and Monteverdian influences are evident, alongside others of more recent origin.

After Credo Pärt reached an impasse both musically and professionally. For several years (from 1968) he concentrated on exploring tonal monody and simple two-part counterpoint in exercises inspired by his studies of early music and Gregorian chant. During this period he produced two works (Laul armastatule – subsequently withdrawn – and the Third Symphony) which reveal the strength of these preoccupations. It was only in 1976, however, that he began to compose fluidly again, this time using a tonal technique of his own creation which he calls ‘tintinnabuli’ (after the bell-like resemblance of notes in a triad). The first piece to be written in this new style was the short piano solo Für Alina.

The majority of Pärt’s works composed after 1980 are for chorus or small vocal ensemble; his choice of texts has ranged from Latin (which predominated at first) to German, Church Slavonic, Spanish, Italian and English. Among the larger works mention should be made of Te Deum which invokes – but does not in fact use – Gregorian chant; Stabat mater, in essence an extended piece of chamber music for double trio (three strings and three voices); Miserere which incorporates an earlier setting (here revised) of the Dies irae sequence; two a cappella choral works, the (Latin) Magnificat and the (German) Seven Magnificat Antiphons; and Litany (1994), the first work since the Third Symphony to employ something approaching a full orchestra; and Kanon Pokajanen, a large-scale a cappella setting of Russian Orthodox texts.

if you are able to come up with what is the most anachronisic element in the staging.

The merits of the Gregorian Chant are known to all; and who that has ever heard it rendered as it should be will not say that it has a divine influence over the soul?

The Latin Liturgy Ass'n had been keeping track of Dies Irae quotes in 'secular' music and was in the high 80's about 10 years ago.

@Unda_Maris: Yes, I was just going to post about Rachmaninov's Isle of the Dead.