Pleiades musicae (1615/1630) is a treatise both conventional and bizarre. Therein author Heinrich Baryphonus (1581–1655) and editor Heinrich Grimm (1592/3–1637)—both cantors, educators, composers, and music theorists working in Protestant north Germany—unfold for the students in their respective towns of Quedlinburg and Magdeburg topics common in music didactic texts from the first half of the seventeenth century: the mathematical origin of intervals, modes, counterpoint, and the fundamentals of composition. The manner of presentation for these typical subjects, however, is rather atypical. Pleiades musicae is astounding in its complex and comprehensive configuration around the number seven, a number that Baryphonus and Grimm assert yokes the fabric of creation. This orientation begins in the opening of the letter to the benevolent reader:

This brief passage abounds with references to esotericism. Describing their work as a “lucubratio”—work done under the cover of darkness— Baryphonus and Grimm point to the secretive nature of their treatise. The invocation of the Pleiades—both the mythological sisters and the stars—in the title signifies otherworldliness. The number seven serves as a powerful organizing agent. Finally, the three domains of knowledge—divine, natural, and political—mirror the three kinds of magic commonly understood in early-modern Germany: celestial, natural, and ceremonial.

Like most seventeenth-century academic texts, the treatise contains an intermingling of intellectual traditions. Aristotelianism is visible in the treatment of Aristotle's three branches of knowledge (theoria, praxis, and poiesis), in the meticulously organized and systematic approach to knowledge, and in the value that the authors place on observable phenomena in the tangible universe. Embracing Ptolemaic compromise, Baryphonus and Grimm recognize both mathematical reason and sensory judgment. Christian doctrine manifests in their Trinitarian approach to triadic harmony, a topic Grimm adds to the second edition. However, Pleiades musicae is most striking in its pervasive expressions of Neoplatonism.