Know'st

"Thou know'st, who oft hast sorrowed with my pain, / how, tost by Juno's rancour, o'er the main / thy brother wanders."

Source: tatoeba (6798633)

When thus the prophet Helenus I hail, / "Troy-born interpreter of Heaven! whose art / the signs of Phoebus' pleasure can impart; / thou know'st the tripod and the Clarian bay, / the stars, the voices of the birds, that dart / on wings with omens laden, speak and say, / (since fate and all the gods foretell a prosperous way / and point to far Italia)."

Source: tatoeba (7063797)