St. Jerome Writing is a confession, composed by Caravaggio in the mode of repentance and atonement.

You can see the effects of this early baroque work in Vermeer, Rembrandt, and many other artists.

Intentionally or not, Caravaggio cultivated a genuine gangster persona: unpredictable, volatile, full of arrogance. St. Jerome Writing shows that he also took his Catholicism seriously, or at least was very good at simulating piety for his patrons. The more mistakes he made, the more his debt to the community, the State, and the Church compounded,  the more devotional and introspective his paintings became. You can see this in the great contrast in mood, setting, composition and chemical makeup between his two paintings of Jerome writing.

The earliest Caravaggios we know of are from his Rome period, before he went on the lam; these paintings, which include St. Jerome Writing and Saint Jerome in Meditation, contain a significant amount of lead white, giving a brightness and luminosity to the canvas which would disappear when the artist fled to Malta, where he would compose his other, much darker, portrait of Jerome writing.

In Saint Jerome Writing, the addition of lead white to the earthen mixtures is seen only in the upper layer. The presence of lead white in the upper ground layer, in direct contact with the paint film, characterizes the impasto, which is still warm and light in tone.

The three Jerome paintings are reflections of the chaotic life of Caravaggio, and the lead may have been one of the reasons for his tragically short career.

Jerome himself was best known for his translation of parts of the Greek New Testament and the Hebrew TaNaKh into Latin, which later became the officially sanctioned text of the Catholic Church, the Vulgate. He was important to the patrons of Caravaggio as a major Catholic apologist, defending the faith against Protestantism, Judaism, and Islam.