If an organism is viewed as an open system in a steady state, a theory of organismic processes can be worked out. Even better, a living organism can be viewed as a hierarchical order of open systems, where each level maintains its structure thanks to continuous change of components at the next lower level. Living organisms maintain themselves in spite of continuous irreversible processes and even proceed towards higher and higher degrees of order. Von Neumann describes the neural system of the brain from a mathematical point of view, i.e. viewed as an automaton, using techniques and concepts of the digital computer. In this postomous book Von Neumann explores the idea that a machine could be programmed to make a copy of itself.
Life is a particular class of automata.
Life's main property is the ability to reproduce. Von Neumann's automaton was conceived to absorb matter from the environment and process it to build another automaton, including a description of itself. A self-reproducing machine is a machine that produces another machine of equal of higher complexity. Turing proved that there exists a universal computing machine. Von Neumann proved that there exists a universal computing machine which, given a description of an automaton, will construct a copy of it, and, by extension, that there exists a universal computing machine which, given a description of a universal computing machine, will construct a copy of it, and, by extension, that there exists a universal computing machine which, given a description of itself, will construct a copy of itself.