Marin Mersenne's Harmonie universelle (Paris, 1636-37) provides a rare insight into French vocal practice of the early 17th c. Although he approaches singing as a teacher or composer, his comments also provide the performer with clues about ornamentation in early-17th-c. French vocal music. His examples of diminutions and explanations of individual ornaments reveal that the practice was significantly different from that of the later part of the century, with which most modern singers are more familiar.
"Mersenne on Vocal Diminutions,"
Performance Practice Review:
2, Article 6.
Available at: https://scholarship.claremont.edu/ppr/vol6/iss2/6