Hesperus

His name is sometimes conflated with the names for his brother, the personification of the planet as the "morning star" Eosphorus (Greek Ἐωσφόρος, "bearer of dawn") or Phosphorus (Ancient Greek: Φωσφόρος, "bearer of light", often translated as "Lucifer" in Latin), since they are all personifications of the same planet Venus.

[5] Maurus Servius Honoratus, in his commentaries on Virgil's Eclogues, mentions that Hesperus inhabited Mount Oeta in Thessaly and that there he had loved the young Hymenaeus, son of Dionysus and Ariadne.

[6] In the philosophy of language, "Hesperus is Phosphorus" is a famous sentence in relation to the semantics of proper names.

Gottlob Frege used the terms "the evening star" (der Abendstern) and "the morning star" (der Morgenstern) to illustrate his distinction between sense and reference, and subsequent philosophers changed the example to "Hesperus is Phosphorus" so that it utilized proper names.

Saul Kripke used the sentence to posit that the knowledge of something necessary (in this case the identity of Hesperus and Phosphorus) could be empirical rather than knowable a priori.