Yehuda ben Moshe ha-Kohen lived during the 13th century and became the personal physician of King Alfonso X of Castile.
He also translated the Lapidario, helped by the Christian Garci Pérez, and the famous Alfonsine tables, compiled by Isaac ibn Sid, that provided data for computing the position of the Sun, Moon and planets relative to the fixed stars.
As a result, it was feared that both Christian kingdoms of Portugal and Spain, which were on the verge of forming an alliance, would change their attitude towards the Jews and would decree their expulsion.
Legend has it that Yehuda ben Moshe decided to take the initiative and traveled to Portugal, where he gained access to the patient and came to the conclusion that the ailing prince was suffering from a blood-clot.
Yehuda performed a very difficult operation that turned out successfully, saving the life of the Prince.