Clavis Cantus Ecclesiastici seu modus intonandi, et cantandi Invitatoria, Psalmos, Antiphonas, Responsoria, Lersiculos, Oectiones, Epistolas, Evangelia, Passionem, Lamentationes, & alia precipua, quae passim occurrunt in Officio Divino cantanda. Iuxta ritum Sacri Ordinis Ff. Praedicatorum, sub Reverendissimo Patre Fr. Io. Baptista De Marinis eiusdem Ord. Magist. Generalis. Romae typis Nicolai Angeli Tinassi, 1661. Full leather completely decorated with gilded friezes impressed on the boards and spine; octavo, 18,2 cm; pp. 290 (but real 286, missing pages 15-16, 63-64 and 291); imperceptible restore to the binding, modern endpapers, 5 missing pages and some little foxing, overall more than good copy. Title page text in red and black, woodcut Guidonian hand on p. 2; woodcut drop caps; musical notations on tetragrammaton. First and very rare edition of this Manual, or “Chiave”, of Ecclesiastical Chant, where all the Holy Offices are present. At the beginning, introduction and explanation of the Guidonian hand and way of applying it. The text then continues with the various songs of the Holy Offices, with notes on how to sing them. Unfortunately missing of five pages but with beautiful binding; not at all a common work.