By the age of twenty, Leonardo da Vinci was a master in the guild of St. Luke, a guild of artists and doctors of
medicine. His ever-increasing thirst for knowledge led his paintings of the human form to be remarkably lifelike. By
taking on the study of anatomy, Leonardo put himself closer to the title of Renaissance man.

What is the meaning of the underlined word (guild) in the passage above? Use your context clues to guide you.