In his book Chance and Necessity, Jacques Monod described the functions of proteins and other molecules capable of recognizing with elective discrimination a substrate or ligand or other molecule. In describing these molecules he introduced the term cognitive functions, the same cognitive functions that Maxwell attributed to his demon. Werner Loewenstein goes further and names these molecules molecular demon<nowiki/> or demon in short.
Naming the biological molecular machines in this way makes it easier to understand the similarities between these molecules and Maxwell's demon.    
Because of this real discriminative if not cognitive property, Jacques Monod attributed a teleonomic function to these biological complexes. Teleonomy implies the idea of an oriented, coherent and constructive activity. Proteins therefore must be considered essential molecular agents in the teleonomic performances of all living beings.