St. Hyacinth was born a noble in 1185. He was well-educated, becoming a Doctor of Law and Divinity. After he finished his schooling, Hyacinth went to Rome and joined the Dominicans, the Order of Preachers. 

He was made superior of a small band of missionaries, and they traveled to Poland to spread the Gospel. They were well-received there, and converted many people who heard their sermons. 

Hyacinth founded communities in Kracow, Sandomir, and elsewhere, and preached in Prussia, Denmark, Sweden, Norway and Russia. He returned to Krakow in 1257, and died on August 15. 

St. Hyacinth is a patron of Poland, and he is known as the apostle of Poland. A few of his relics are kept in the Dominican church in Paris.