Ghiberti was now widely recognized as a celebrity and the top artist in this field. He was showered with commissions, even from the pope. In 1424 he received a second commission, this time for the east doors of the baptistery, on which he and his workshop (including Michelozzo and Benozzo Gozzoli) toiled for 27 years, excelling themselves. These had ten panels depicting scenes from the Old Testament, and were in turn installed on the east side. The panels are large rectangles and are no longer embedded in the traditional Gothic quatrefoil, as in the previous doors. Ghiberti employed the recently discovered principles of perspective to give depth to his compositions. Each panel depicts more than one episode. In "The Story of Joseph" is portrayed the narrative scheme of "Joseph Cast by His Brethren into the Well", "Joseph Sold to the Merchants", "The merchants delivering Joseph to the pharaoh", "Joseph Interpreting the Pharaoh's dream", "The Pharaoh Paying him Honour", "Jacob Sends His Sons to Egypt" and "Joseph Recognizes His Brothers and Returns Home". According to Vasari's "Lives", this panel was the most difficult and also the most beautiful. The figures are distributed in very low relief in a perspective space (a technique invented by Donatello and called "rilievo schiacciato", which literally means "flattened relief"). Ghiberti uses different sculptural techniques, from incised lines to almost free-standing figure sculpture, within the panels, further accentuating the sense of space.