He occupies a conspicuous place among the ornamental painters, but his works in this way would be more perfect if there was not so great a redundance of decoration, as vases, festoons, and figures of boys in the cornices, though this indeed was the taste of the age. The ceiling of the church of S. Ignatius is his greatest work, and which would serve to show his powers, if he had left nothing else, as it exhibits a novelty of images, an amenity of colour, and a picturesque spirit, which attracted even the admiration of Maratta and Ciro Ferri; the last of whom, amazed that Andrea had in so few years, and in so masterly a manner, peopled, as he called it, this Piazza Navona, concluded that the horses of other artists went at a common pace, but those of Pozzo on the gallop. He is the most eminent of perspective painters, and even in the concaves has given a convex appearance to the pieces of architecture represented, as in the Tribune of Frascati, where he painted the Circumcision of Jesus Christ, and in a corridor of the Gesù at Rome. He succeeded too in a surprising manner in deceiving the eye with fictitious cupolas in many churches of his order; in Turin, Modena, Mondovi, Arezzo, Montepulciano, Rome, and Vienna, to which city he was invited by the emperor Leopold I. He also painted scenes for the theatres, and introduced colonnades and palaces with such inimitable art, that it renders more credible the wonderful accounts handed down to us by Vitruvius and Pliny of the skill of the ancients in this art. Although well grounded in the theory of optics, as his two volumes of perspective prove, it was his custom never to draw a line without first having made a model, and thus ascertained the correct distribution of the light and shade. When he painted on canvass, he laid on a light coat of gum, and rejected the use of chalk, thinking that when the colours were applied, the latter prevented the softening of the lights and shadows, when requisite. He had many scholars who imitated him in perspective; some in fresco; others in oil, taking their designs from real buildings, and at other times painting from their own inventions. One of these was Alberto Carlieri, a Roman, a painter also of small figures, of whom Orlandi makes mention. Antonio Colli, another of his scholars, painted the great altar at S. Pantaleo, and decorated it in perspective in so beautiful a manner, that it was by some taken for the work of his master. Of Agostino Collaceroni of Bologna, considered of the same school, we have before spoken.