The Appendix Probi ("Appendix of Probus") is a palimpsest appended to the Instituta Artium, a work written in the third or fourth century AD by the grammarian Valerius Probus. The text only survives in a manuscript of the seventh or eighth century.[1] In the past it was attributed to Probus, but this is now considered erroneous.[2]
The Appendix lists common mistakes in the written Latin of the time. In these mistakes, we can observe tendencies in the grammar, spelling, and pronunciation of the contemporary vernacular which would become the various Romance languages. The author's corrections of these usages give us insight into how Latin was evolving at that time. For example, the instruction PASSIM NON PASSI ("passim, not passi") or NVMQVAM NON NVMQVA ("numquam, not numqua") tells the reader that the Classical Latin word is written with an M. The fact that this was a common spelling error suggests that word-final M had become silent. Many of these mistakes later became well-and-truly standard, cf. Spanish nunca, from NVMQVAM (nunquam). In some cases, the document recommends forms that are not the usual Classical ones, for example AMFORA NON AMPORA ("amfora, not ampora") recommends an F, whereas amphora is normally spelled with PH.