Martin inherited the features and dark complexion of his mother, and for that reason his noble father eventually turned the boy out of his house. After a turn as a surgeon's apprentice, the young man joined the Dominicans as a laybrother and was put in charge of the infirmary of a friary in Lima. Soon he was caring for the sick of the city and the slaves brought to Peru from Africa — not to mention the animals with which he is often pictured. Martin had the gift of miracles; and although he had no formal training, he was often consulted on theological questions by great churchmen of his day. St. Rose of Lima and Bl. John Massias were among his close friends.
He is unofficially called the patron of social justice.