“Men, it has been well said, think in herds; it will be seen that they go mad in herds, while they only recover their senses slowly, and one by one.”
From the preface of the 1852 classic, “MEMOIRS OF EXTRAORDINARY POPULAR DELUSIONS AND THE Madness of Crowds,” by CHARLES MACKAY.
I recommend it to everyone. Available in its entirety at
http://www.gutenberg.org/files/24518/24518-h/dvi.html
Excellent book.