http://seedmagazine.com/content/article/the_meaning_of_life/
http://astrobiology.nasa.gov/articles/what-is-life-definition-vs-theory/
d/dx is a universal operator in math that is applied to a function. The study of Life (biology) lacks this operator because we can't define life. Epicureans try to emulate d/dx by invoking the term NS, which as some sort of universal mechanism is no more plausible than a single differential equation explaining all of physics. Alchemy was only stopped after Gold and lead were defined in terms of molecular theory. Prof. Cleland from Nasa astrobiology pointed out that before the discovery that water is H20, acids were called 'weak' and 'strong' water. Likewise the very thing that Epicureans claims to study - Life(biology) itself - isn't defined, and thus we don't know whether anything analogous to d/dx is applicable - Life1 . See also calls Darwin's theories 'weak'.