Jean Polit, lawyer and poet, was born in Liège around 1554. He studied in his home town. In 1578 he wrote a collection of poems for Gerard of Groesbeck, Prince Bishop of Liège (1563-1580), to whom eight years earlier De Castro had dedicated a book of chansons and madrigals. By 1588 Polit was appointed historiographer of Ernst of Bavaria at the archiepiscopal court of Cologne.In 1588 he produced a book on the history of Liège (starting from the age of Caesar): the Panegyrici ad christiani orbis principes, which he had published in Cologne and dedicated to Cesare Homodei, for whom in the same year De Castro composed a music volume. Polit's history of Liège also contained a series of odes, addressed to the social and political fine fleur of Cologne, most of whom had an influential position at the court. Several names return among the patrons of De Castro's new Cologne music books (Cesare Homodei, Paul Stor, Karel Billehé). Undoubtedly Polit introduced his friend in the highstanding milieu of the court of Ernst.
Still in 1588 the poet wrote a poem in praise of De Castro which was inserted in the latter's motet book for Ernst of Cologne of the same year.