[5] Apart from the regular later title of "first historian of the Roman Baroque", in his lifetime he was also nicknamed Il Sordo del Barozzo as he suffered from deafness.

[6] He published two books, The nine churches of Rome (Le nove chiese di Roma 1639),[7] and The Lives of Painters, Sculptors, Architects and Engravers, active from 1572–1642 (Le Vite de' Pittori, scultori, architetti, ed Intagliatori dal Pontificato di Gregorio XII del 1572. fino a' tempi de Papa Urbano VIII.

Relatively few other sources, other than contracts and the like, exist for most of these figures, and Baglione's work often remains the basis for their biographies, being drawn on extensively by Bellori, Passeri and others, as well as modern writers.

[9] Baglione had known a large number of his subjects personally and his attributions and basic factual information is considered generally reliable, although like Vasari and most intervening biographers of artists, he sometimes repeats anecdotes uncritically.

He carefully notes information about the social status and progress of his subjects, and is often very quick to criticise and moralize over human failings and bad habits.

He "recorded all signs of social status, including houses, dress, collections, permission to wear a sword, splendid funerals, and tombs."

Similarly, he never failed to mention if an artist was a member of his beloved Academy of St. Luke, had been elected to the Virtuosi del Pantheon, had been knighted, had been well paid for his work, or had been employed by noble patrons.

Running throughout Le vite, in other words, is an abiding concern with the honor of the profession-with the elevated status and nobilta of the artist as gentleman.

Baglione's painting exists in two versions, the earlier in the Gemäldegalerie, Berlin (c. 1602–03) and the later in the Galleria Nazionale d'Arte Antica at Palazzo Barberini in Rome.

Baglione had recently completed his large altarpiece of the Resurrection of Jesus for Il Gesu, the main church of the Jesuit Order (it was much later replaced), and claimed that Caravaggio was jealous of this important commission.