Hieronymus machines were the ostensible invention of Dr. Thomas Galen Hieronymus (21 November 1895 – 1988). As explaine mostly by Astounding Science Fiction editor John W. Campbell in late 1950s and early 1960s editorials, Hieronymus machines were mock-ups of real machines (patented by their inventor) which allegedly worked by analogy or symbolism, being directed by psi or ESP powers.