At the temple of Esna, the seated baboon sign obtains several phonetic and ideographic values. In addition to previously recognized usages, this hieroglyph also represents the copula pronoun pw, which at the time should have been pronounced ip. Although apparently limited to Esna, this value occurs in over twenty examples, spanning the full diachronic range of the inscriptions. All examples are translated with detailed commentary. In an appendix, four additional, previously unrecorded values of the seated baboon sign are discussed.