His gift of preaching was soon evident. He journeyed tirelessly through the territory of Andalusia of Spain, speaking in small towns and crowded cities. His words were able to touch the minds and hearts of young and old, rich and poor, students and professors. His work in the confessional completed the conversions his words began.
This unlearned man was called "the apostle of the Holy Trinity" because of his devotion to the Trinity and the ease with which he preached about this sublime mystery. One day a child gave away his secret, crying out: "Mother, mother, see the dove resting on the shoulder of Father Didacus! I could preach like that too if a dove told me all that I should say."
Didacus was that close to God, spending nights in prayer and preparing for his sermons by severe penances. His reply to those who criticized him: "My sins and the sins of the people compel me to do it. Those who have been charged with the conversions of sinners must remember that the Lord has imposed on them the sins of all their clients."
It is said that sometimes when he preached on the love of God he would be elevated above the pulpit. Crowds in village and town squares were entranced by his words and would attempt to tear off pieces of his habit as he passed by.
He died in 1801 at age 58, a holy and revered man. He was beatified in 1894.