 Mary 's left hand is on an open prayer @-@ book , propped on a prie @-@ dieu ; the letter " D " visible on the page – perhaps for Deus <unk> ( " the Lord be with you " ) , according to Ainsworth . Blum speculates the passage is from Isaiah 7 : 14 , " Behold a Virgin shall conceive and bear a son . " A vase containing white lilies and a single blue iris is next to it on the floor . 
