Antonino Pierozzi, Archbishop of Florence in the mid-15th century, described extensively the miraculous in utero conception of Jesus. Lippi, in his London Annunciation, superseded theological interpretation and ventured into optics: namely Roger Bacon's theory of the "multiplication of species", which had been excerpted by Ghiberti in Book III of his Commentarii and was therefore well known to artists. The evidence is convincing that Lippi thought out the pictorial solution to this painting with Bacon in mind. When he painted the dove opposite Mary's womb, he was thinking that distinct vision occurs only when the visual object confronts the eye and the visual rays are able to enter at right angles. The second hint of Lippi's debt to Bacon's optics is the way he represented the species coming from the dove to the Virgin. Only one ray issuing from the dove connects with the center of the light emanating from the Virgin's womb. It is also the most nearly perpendicular. The little cut in Mary's garment represents the pupil of an eye.