This paper looks at the interest shown early in the twentieth century in the so-called primitive mind, and in particular to its expression in the behaviour of the crowd, the mob and the herd. Many of the scientists working during this period suspected that human civilization ran the risk of regressing to a more ancient condition, within which violence and destructive instincts were apt to make a regrettable reappearance.

Psychology was beginning to emerge as a natural science rather than as a branch of metaphysical philosophy, partly due to experimental work on perception, memory and reaction times; partly due to the widely-accepted concepts of the theory of evolution; and partly as a result of the work going on in the field of clinical hypnosis.