Giovanni (or Johannes) di Casali (or da Casale; c. 1320 – after 1374) was a friar in the Franciscan Order, a natural philosopher and a theologian, author of works on theology and science, and a papal legate.
He was born in Casale Monferrato around 1320[1] and entered the Franciscan order in the Genoese province.
In 1375 Pope Gregory XI appointed him papal legate to the court of King Frederick of Sicily.
[2] About 1346 he wrote a treatise De velocitate motus alterationis (On the Velocity of the Motion of Alteration) which was subsequently printed in Venice in 1505.
His teachings in mathematical physics influenced scholars at the University of Padua and, it is believed, may have ultimately influenced the similar ideas presented over two centuries later by Galileo Galilei.