"When the brightest of all stars came up, the star which often ushers in the tender light of early Dawn"

The star referred to here is Eosphorus or Phosphorus (‘Dawn-bearer’), the morning star and son of Eos. His brother, Hesperus, was the evening star. The early Greeks who first named them did not realise that the morning star and evening star are not two separate bodies, or actually even stars, but are in fact both the planet Venus, shining brightly at dawn and dusk.