For many years Christian Science has explained how the suppositional mortal mind claims to be general and to suggest itself as real to all in similar ways. Whatever argument of destructiveness this illusory carnal mind would claim to suggest to one, it would also claim to be able to suggest to others. On pages 153 and 154 of "Science and Health with Key to the Scriptures" by Mary Baker Eddy, there is a paragraph which gives familiar illustrations of this tendency: "We weep because others weep, we yawn because they yawn, and we have smallpox because others have it; but mortal mind, not matter, contains and carries the infection. When this mental contagion is understood, we shall be more careful of our mental conditions, and we shall avoid loquacious tattling about disease, as we would avoid advocating crime. Neither sympathy nor society should ever tempt us to cherish error in any form, and certainly we should not be error's advocate."
It is interesting to see modern psychologists adopting Mrs. Eddy's analysis and recognizing that the belief in contagion is much more widespread and subtle than that form of contagion which has been accounted for by a mere germ theory. In contemporary psychology there is considerable discussion of "pandemic psychosis" and "mental contagion." What are loosely called "popular crazes" and "mob psychology" are being studied with an intensity that is quite in keeping with the states of the human mind thus analyzed. Dr. James Hendrie Lloyd explains, for instance, in a recent article, that "the mental pathologist has even invented a name for this sort of movement and calls it a 'pandemic psychosis'; that is to say, a functional mental disorder which tends to spread over large numbers of people. Its chief characteristic, indeed, is this tendency to spread; it is like the cholera or the smallpox in so far as it pursues what may be called a centrifugal course. It grows out of what has been somewhat crudely called 'mob psychology,' but a better term is mental contagion, because the analogy to the contagious diseases is complete."
Much of the hatred and unjust coercion shown during the war in "drives" for contributions that should have been entirely voluntary was an evidence of this mental contagion. Lynching, the practice of terrorism by temporarily rampant majorities or even minorities, and the tendency to hysteria in almost any crowd that allows itself to be emotionally stimulated, are other phases of the same belief. When people congregate, mortal mind would ever like to substitute an emotional fury, centering around some one human opinion, for calm reasoning in accord with Principle.