Dr. Behe argues that the common mousetrap can point one to God. This invention, like many things that are found in biological systems, is “irreducibly complex”—that is, it only functions when all of its component parts are present. Using the example of the mousetrap, Dr. Behe explains in depth why many such irreducibly complex things such as the human eye present problems for Darwinian theory. The existence of biological systems that cannot evolve gradually, argues Dr. Behe, is a compelling argument that the patterns of nature did not arise by chance, but rather are the products of a Designer.