"Thought Control in Everyday Life"
James Alexander
(United States: Funk & Wagnalls Company, 1928) pages 233-234

The word “crowd,” … means a collective body of men and women – people gathered together for some purpose in common.

For the average man – the man with neither knowledge of Crowd Psychology, nor training in thought control – one of the most difficult things in the world is to control his thoughts when he is a member of a crowd. For the crowd, no matter what its constitution may be, whether made up of men of good birth and education, or men with neither of these advantages, ranks as the lowest form of human association.

The crowd is a collective mind with little intelligence, and is largely dominated by its instincts and emotions. Attend a congress of any body of men and women; observe them carefully, and you will note how large a part the instincts and emotions play, and the far from high quality of the display of intelligence. You will see highly intelligent men and women, whom you have heard about or read of, and you will go home with a quite different conception of them; for you will judge them by their actions and the part they in the discussions. Most observers, in such conditions, will judge wrongly. For crowds are contagious, their speech and acts are contagious, and, for the time being, every man and woman in a crowd is a very different individual from what he or she is in private and in ordinary life. Any person who doubts this has only to make the experiment. Let him mix with any crowd where feeling runs high and opinions clash, and let him note the effect on his own mentality. One thing is sure to strike [the individual] when a member of such a crowd – the enormous power of suggestion and a weakening of his own power to resist its influence.

... The great thing to grasp is that the crowd mind is antagonistic to the individual mind. The crowd mind demands that you, as a member of the crowd, should think as it thinks. Never lose sight of that fact; be determined to think for yourself, and panic thoughts will have little power over you. One word more: watch closely your emotions when you are a member of a crowd; never allow them to develop; switch the mind away to the cool, calm, collected attitude of mind.