While waiting to redo the first painting of the cycle that had been rejected by his clients, in 1600 Caravaggio created the side paintings of Contarelli Chapel, which constituted an epochal turning point in the history of art.
Start with the first painting he made, called The Martyrdom of St. Matthew; it takes place in a church, while the saint is about to baptize some youth, but a slayer bursts into the church and stabs the priest during Mass. It is a brutal execution, depicted like a crime scene in the news: Caravaggio puts you in front of the "live" scene, at its most dramatic moment. St. Matthew is on the ground, trying to defend himself in vain, while the assassin's shouts are echoed by those of the altar boy, who runs away frightened. Caravaggio is also present, depicting himself to the left of the assassin as the figure with the goatee watching the saint's execution. This expedient adds incredible realism to the narrated scene, which seems to take place in the present, and not in a distant past.
Now move on to the painting entitled The Calling of St. Matthew. Caravaggio immortalizes the moment when Christ invites the tax collector to become his disciple. A ray of light from the right is projected onto the wall, which is how you must examine the painting, starting from Christ's invitation to the surprised Matthew who points a finger at his chest. As you can see, light dominates the scene and subdivides it into two registers: the lower shadow is full of figures, while the top is illuminated by the ray entering from the window.
Finally, move on to the newer version of the painting entitled The Inspiration of Saint Matthew, which Caravaggio painted in 1602. Even if it slightly attenuates the crudeness of his first version, the painter didn't eliminate the saint's informal pose. Yet notice how intense the silent dialogue between the angel and the saint is: he seems to draw inspiration for what he will write in his Gospel from their profound exchange of glances.
FUN FACT: Caravaggio was famous for his fiery temper. The waiter at an inn once brought him a plate of artichokes in which some had been cooked in oil and others in butter. When the painter protested, the waiter replied that all he had to do was sniff them to figure out which was which. That set Caravaggio off, who threw the dish at the boy and chased him around the inn with his sword unsheathed!