florence had a republic in which you could be coming from the arab world because constan nopal fell andou're bringing the algebra from the arab world and you're accepted. so it's a lesson for us today which is sort of loving the diversity of people around us often helps become a affirmative of cradle of creativity. >> let's get into the great paintings. obviously the mona lisa, the last supper and i want to ask you first about again his incredible curiosity and his unbelievable research. i read that he went to morgues, peeled back the skin of cadavers to figure out the connection -- the anatomy of a smile. >> absolutely. the mona lisa is the best example of the combination of art and science. other people -- art critics have written about leonardo it's a shame he wasted so much time on anatomy because he could have painted more paintings. well, no, he may have painted more paintings but he wouldn't have painted the mona lisa. if you look at the smile, he has over a period of three years dissected every muscle and nerve in the human face and he's starting to sketch faint smiles. he's dis