  We discuss the role of combinators in the development of the modern
conception of computation over the course of the past century. We describe how
ideas about formalism and mathematical logic led to the introduction of
combinators in 1920 as an extension of the discovery of Nand as a basis for
basic logic. We then discuss how combinators informed lambda calculus and
symbolic computation, and their relationship to the development of practical
computation. We finally describe recent views of combinators in terms of the
computational universe of possible programs, and a recent approach to the
fundamental theory of physics.
