The Roman Catholic Church here is on a mission to document a miracle that can be attributed to one of the country’s most popular folk heroes: José Gregorio Hernández. In 1986, Pope John Paul II declared Dr. Hernández “venerable,” a step toward being considered for sainthood. To take the next step, known as beatification, the church would need to show that Dr. Hernández had performed a miracle. Once that was done, proof of a second miracle could qualify him to be canonized, or declared a saint. Now, with the 150th anniversary of Dr. Hernández’s birth approaching, the church here has started a campaign to find the miracles needed to propel him to sainthood.