That duality link is inherent to the human reaction to skulls, it seems to me – on the one hand, the skull obviously invokes death and mortality, link but on the other hand, it is to the part of link the brain that recognizes people, a face as well, albeit one with a limited repertoire of expressions. Even there, though, the longer you stare at one, the more fluid the expression seems – is it laughing, or do the downturned corners of the eye sockets seem sad? link