[2] In 1662, he was accepted into the Roman artists' guild, the Accademia di San Luca (Academy of Saint Luke), where he was to later hold several offices.
In the first half of the 17th century, two counter-reformation "mother" churches (Sant'Andrea of the Theatines and the Chiesa Nuova of the Oratorians) had been extensively decorated.
A new inductee into the order, the French Jacques Courtois (also known as Giacomo Borgognone) had become a respected painter and was the main candidate for its decoration.
Ultimately, with Bernini's persuasive support and likely strong guidance thereafter, Oliva awarded the prestigious commission to the mere 22-year-old Gaulli.
[3] Gaulli decorated the entire dome including lantern and pendentives, central vault, window recesses, and transepts' ceilings.
During this time, Bernini supposedly espoused some quietist teachings of the Spanish priest Miguel de Molinos, who was later condemned as heretical in no small part due to Jesuit efforts.
Thus Oliva would have likely asked Gaulli to memorialize the role of frequently-martyred Jesuits as the apostolic shock troops in heretical and pagan societies, leading the charge of the papal Counter-Reformation.
Swirling figures in the dark distal (entry) border of the composition frame base the open sky, ever rising upward toward a celestial vision of infinite depth.
[5] The light from Jesus' name - IHS - and symbol of the Jesuit order is gathered by patrons and saints above the clouds; while in the darkness below, a fusillade of brilliance scatters heretics, as if smitten by blasts of the Last Judgment.
[7] Gaulli's frescoes were a tour-de-force in illusionary painting, depicting the church's roof opens up above the viewer (and that the panorama is viewed in true perspective di sotto in su, similar to Correggio's frescoed dome ceiling depicting the Assumption of the Virgin or to Cortona's grand allegory at the Palazzo Barberini.
[9] He was described as easy to mount a rage; but ready to recover, where reason was satisfied... generous, liberal of mind, and charitable, specially towards the poor.