The formal study of both astronomy and astrology in later medieval Europe was firmly based in the universities. Instruction in astrology is attested by the presence of an educational board game, known as the ludus astronomorum, in several university-related miscellanies of fifteenth-century English provenance. William Fulke also published an edition of the game a century later (Ouranomachia, London, 1571), which is attested in a number of Elizabethan libraries. The game serves to rehearse for its players the celestial motions and astrological principles described by Ptolemy. It also employs principles of stellar rays described by al-Kindi in his De radiis stellarum.