Theophylact Simocatta
Copernicus, born in 1473 and already well over 60 years old, had never published any astronomical work, as his only publication had been his translation of poems of Theophylact Simocatta, printed in 1509 by Johann Haller. At the same time, he had distributed his ideas among friends, with manuscripts called "Commentariolus". In the 1530s, he was urged to publish by many, yet still hesitated when in 1539, Rheticus arrived in Frauenburg (Frombork) to become Copernicus' first and only pupil. Philipp Melanchthon had arranged for Rheticus to visit several astronomers and study with them.