The centre nave, above the columns, is done in mosaic.  On the right side, above the columns, all the generations contained in the Gospel of the book of generation of Jesus Christ, beginning with Abraham down to Christ, are worked and figured together.  On the left side are figured all the generations contained in Gospel of one of the Evangelists [here is described the order according to Matthew 1.1-17 while on the left side according to Luke 3.23-38], who says: factum est, cum omnis populus baptizaretur, etc., beginning from Heli and then from Mathar, and so back to Adam, all in mosaic with inscriptions in Latin and Greek.  To the east, above the main door, which does not open, is figured, also in mosaic, the tree which springs from Abraham’s side.  In the first branch is Isaac, in the second Jacob, and so on in the other branches all the prophets who foretold Jesus Christ, each of them with his prophecy in hand, how from that generation Jesus descended. … In front of the choir there is a door, behind which is the high altar; in front there is an apse, in which is represented in mosaic the Virgin Mary, with Abraham and David on either side.