@2001grandCreation argues that life is a particular kind of autocatalytic network in which enzymes, the complicated molecules that facilitate reactions between other complicated molecules, are themselves consequences of reactions between simple inorganic substances like carbon dioxide and water; taken all together, this self-maintenance is what we call metabolism. These networks are not made of the same atoms in each moment, but “self-maintaining patterns in space and time in their own right—persistent eddies in a flowing stream of molecules and ions.”
Stuart Kauffman’s work on the mathematics of such networks shows that they can emerge spontaneously, and thus claims in At Home in the Universe:
Life, at its root, lies in the property of catalytic closure among a collection of molecular species. Alone, each molecular species is dead. Jointly, once catalytic closure among them is achieved, the collective system of molecules is alive.
Grand extends this theory by proposing two additional conditions for life’s persistence: encapsulation and encoding.