Just in case you missed this very special illusion from my August 2007 archives, it bares repeating.
Sit back and tilt your head just slightly to the left staring intently at the corner of the old man's mouth.
Click on the following link to see a more detailed examination of this sketch and many more hidden images I've actually outlined for you: http://www.n2davinciandbeyond.com/n_2_da_vinci_and_beyond_b/2007/10/da-vinci-art-of.html
Main page: www.n2davinciandbeyond.com/
N 2 DA VINCI AND BEYOND...