Pareja worked for Velazquez from the 1630s onward, carrying out the practical labour that kept a great painter's workshop running: grinding pigments, priming canvases and producing copies of finished works so skilled that a number were once mistaken for Velazquez's own hand^[1]. He gained his freedom in Rome in the autumn of 1650, during Velazquez's second visit to Italy, a journey on which Velazquez painted more portraits than in the whole of the following decade back at the Spanish court^[1]. Rather than leaving on receiving his freedom, Pareja chose to continue working alongside Velazquez for another ten years, until Velazquez's death, a continuity that says as much about the working relationship between the two men as any single anecdote could.

Pareja is best remembered today through Velazquez's own 1649 or 1650 portrait of him, painted in Rome and, according to tradition, undertaken partly as practice before Velazquez's celebrated portrait of Pope Innocent X, though the finished picture reads as more than a study; it was exhibited publicly at the Pantheon's portico in May 1650 alongside works by other painters resident in the city, seemingly as a deliberate demonstration of Velazquez's skill to his Italian rivals^[2]. The portrait's fame has tended to overshadow Pareja's own work as an independent painter, even though contemporaries regarded him as a genuine talent: Antonio Palomino, whose Lives and Works of the Most Eminent Spanish Artists remains one of the principal sources for Spanish painting of this period, included Pareja in his account of eminent Spanish painters and sculptors, a distinction he did not extend lightly^[3][4].

The Calling of Saint Matthew, drawn from Matthew's own Gospel account of Christ calling the tax collector to become a disciple, was a familiar subject for Baroque painters across Spain and Italy, most famously treated by Caravaggio in his celebrated canvas for the Contarelli Chapel in Rome around 1599 to 1600, which shows Christ pointing toward Matthew amid a group of men counting coins at a table, light falling dramatically across the tax collector's startled face^[4][5]. Tax collectors of the period were widely regarded as sinners, seen as agents of an oppressive Roman government who often extorted more than what was owed, which made Matthew's sudden repentance and calling a powerful, popular image of God's forgiveness^[5]. Pareja's decision to paint this well-established subject on his own account, rather than as a studio assistant's exercise, marks it as a statement of his standing as an independent religious painter in his own right.