Born in 1170 in Caleruega, a mountain village in Old Castile (Spain), he was a regular cleric in the diocese of Toulouse. Supported by his bishop, he founded the Order of Preachers, which, born on the Augustinian Rule, essentially became something totally new, based on itinerant preaching, begging, and in-depth study. Exhausted by apostolic work and worn out by great penances, on August 6th, 1221, he died surrounded by his friars in the convent of Bologna.
The Holy Father, Dominic, died in Bologna on August 6, but Gregory IX, by canonizing him on July 3th, 1234, avoided the conflict with the feast of San Sisto, that was celebrated on that day. He set the commemoration of the founder of the Preachers on August 5th. Then, in 1518, Paul IV wanted to extend the celebration of the Our Lady of the Snow to the whole of Christianity, celebrated on August 5th, he anticipated the feast of St. Dominic to the 4th. The recent liturgical reform has definitively fixed it on August 8th. Only in Bologna is the feast celebrated on the now traditional date of August 4th (from the Little Breviary, EDS, P. Pietro Lippini OP, pp. 531-532).