A Dominican layman from the 16th century, St. John Macias was friends with St. Martin de Porres and helped him in his daily duties.
The Nashville Dominicans offer a brief explanation of his primary duties.
One of Juan Macias’ chief duties was to meet the poor who came to the convent seeking material or spiritual assistance, often more than 200 people every day. Besides his cheerful disposition and encouraging manner, Juan Macias became known for the sometimes miraculous nature of his service to the poor. Everyone knew that Juan worked extremely hard to collect alms for distribution. Still, he would often return empty handed. Yet, somehow Juan never turned anyone away.
Furthermore, his friendship with St. Martin de Porres, another Dominican saint, would eventually lead to a join beatification ceremony.
The two saints often met on their daily rounds of the city and became close spiritual friends as well. They were a constant source of encouragement and ideas for one another. The two were beatified together in a single ceremony by Pope Gregory XVI in 1837.
During his life, St. John Macias would frequently pray for the souls in purgatory with his rosary, as the Confraternity of Intercessors for the Souls in Purgatory explains on their website.
The iconography represents St. John Macias freeing the souls of purgatory with the rosary. The saint always carried the rosary that his mother left him as an inheritance. Because of his constant praying of the Rosary for the souls in purgatory, his biographers call him the "thief of purgatory".
His example reminds us of the need to pray for souls in purgatory and the power of intercessory prayer.