The Scientia artis musice, a music theory treatise completed in the year 1274 by Hélie Salomon, a cleric from the village of St-Astier (Périgord/Dordogne), covers all the usual topics treated in such sources: letter names, hexachord syllables, the claves (letter + syllable(s)), the musical hand, mutation, staff notation, clef placement and chant genres. It includes an incomplete tonary with representative chant genres together with a commentary on the seculorum (differentiae) appropriate to various chant incipits. A lengthy instruction on the performance of parallel four-voice organum is also included. The Scientia is the only medieval theory treatise whose eight illustrations (called ‘figurae’) include human figures. These images relate directly to matters covered in the treatise and serve to make its main points more easily committed to memory. Of especial interest is the image of an enthroned bishop that serves as the focal point for a novel exposition of the tonal system of chant as (1) a set of logical relations modelled after the Tree of Porphyry and (2) a variant of the tree of consanguinity. Since the sole surviving copy of the treatise is the original, all these details must reflect the author's intention.

The biography of Pope Celestine I (422–32) in the first edition of the Liber pontificalis (c.530) credits him with introducing the singing of ‘psalmi ante sacrificium’ at Mass. Several decades later, the second edition added that these psalms were sung ‘antephanatim ex omnibus’. Since the early ninth century, these statements have been interpreted to mean that Celestine introduced the introit chant, a conclusion challenged for the first time about twenty-five years ago. The new interpretation of the passage proposed that Celestine did not introduce the introit, but the responsorial psalm sung between the (two) readings at Mass. An analysis of the terminology used in Celestine's biography, especially the word sacrificium, indicates that the Liber pontificalis author did most likely intend to attribute to him the introduction of the introit, which was certainly in existence by the early sixth century. The presence of a processional solea in certain churches of Rome and the North Adriatic littoral indicates that architectural accommodations were being made for the entrance procession by the fifth century. Psalmic texts form the basis of the repertoire, and non-psalmic introits give every indication of post-dating those with texts drawn from the Psalter.

Three of the articles in this issue of Plainsong & Medieval Music were presented at a session devoted to medieval saints' offices sponsored by the Plainsong and Mediaeval Music Society at the 1999 International Medieval Congress at the University of Leeds. Two of the papers (Caldwell, Hiley) are devoted to English saints, while a third (Hankeln) surveys offices, monastic and secular, of the sainted royal patrons of the diocese of Bamberg, Henry and Kunigunde. Elizabeth Leach's article on the four-voice balades of Guillaume de Machaut brings together considerations of transmission, fourteenth-century contrapuntal theory, and performance practice.

Beginning with this issue of Plainsong & Medieval Music every article will be preceded by a short abstract. Brief identifications of the authors, who will most likely be already known to readers in the relatively small field of medieval music research, will include their e-mail addresses.

In the introduction to the second volume of the series Monumenta Monodica Medii Aevi, devoted in the main to a transcription of the Old Roman gradual Vat. lat. 5319, Bruno Stäblein drew up a perceptive assessment of the native Italian chant style, contrasting it with the melodic style of Gregorian chant, a repertoire considered by many scholars to be the result of a process of local ‘editing’ of the Roman chant introduced north of the Alps in the late eighth and early ninth centuries. Stäblein quoted a remark about the singing of ‘alleluia’ from Cassiodorus' commentary on Psalm 104: ‘The tongues of cantors are adorned with [alleluia], and the Lord's basilica joyfully responds with it. Innovations are always being introduced to it with varying tropes’ (tropis semper variantibus innovatur).