This chapter, 2:17 (“Of the Proportion of Sounds and Harmony”), occupies a significant place in Agrippa's systematic exposition of occult philosophy. In the 1533 Cologne printed edition (De occulta philosophia libri tres, sigla K in Perrone Compagni's critical apparatus), the text represents Agrippa's mature formulation of the ideas it addresses, the product of over two decades of reading, travel, and revision since the composition of the Würzburg draft.

According to Perrone Compagni's table of comparison, this chapter is entirely new in the 1533 edition: it has no antecedent in the Würzburg draft (W). Its presence marks one of the conceptual expansions that distinguish K from W — the addition of material reflecting Agrippa's subsequent reading and intellectual development.

The absence of this chapter from the Würzburg draft invites reflection on what prompted its insertion in the mature edition. Agrippa's intellectual biography between 1510 and 1530 — including his engagement with Neoplatonism, Kabbalah, Hermetism, and scholastic natural philosophy — provides the context for understanding such additions. The partial edition A (sigla A in Perrone Compagni) may offer clues about when the material was composed.