(Lat.: ‘perfection’).
A term used in theoretical writings on mensural music from the mid-13th century onwards. It refers to a quality of ligatures that depended on the value of the final note of the ligature. The final note was normally assumed to be a long unless its normal shape was modified. If the last note was of normal shape (for an ascending ligature this meant with a stem descending to the right, for a descending ligature this meant without stem) then the ligature had perfection and the last note was a long. If the ascending ligature ended in a note with no descending stem, or if the descending ligature ended in two notes in an oblique form, then the ligature had no perfection and the last note was a breve. A quality of ligatures that depended on the value of the initial note of the ligature, Proprietas (‘propriety’), was governed by similar rules, which for a two-note ligature cum opposita proprietate (which had an ascending stem to the left) overruled the above conventions governing perfection and resulted in a pair of semibreves. The usual shapes for two-note ligatures are shown in Table 1. Ligatures of three, four and more notes were governed by the same rules, with all but the first and last notes understood to be breves (except in the case of opposite propriety, when the second note was always a semibreve, or where a note is graphically distinguished as a long or a maxima).
See also Rhythmic modes and Notation, §III, 2 (viii) and 3 (ii).
F. Reckow: ‘Proprietas und Perfectio: zur Geschichte des Rhythmus, seiner Aufzeichnung und Terminologie im 13. Jahrhundert’, AcM, xxxix (1967), 115–43
W. Frobenius: ‘Perfectio’ (1973), HMT
Peter Wright