divide the several reasons to a nice and curious reader, how this
numerical difference in the brain can produce effects of so vast a
difference from the same vapour as to be the sole point of
individuation between Alexander the Great, Jack of Leyden, and
Monsieur Des Cartes. The present argument is the most abstracted
that ever I engaged in; it strains my faculties to their highest
stretch, and I desire the reader to attend with utmost perpensity,
for I now proceed to unravel this knotty point.

There is in mankind a certain . . . Hic multa . . . desiderantur. .
. and this I take to be a clear solution of the matter.

Having, therefore, so narrowly passed through this intricate
difficulty, the reader will, I am sure, agree with me in the
conclusion that, if the moderns mean by madness only a disturbance
or transposition of the brain, by force of certain vapours issuing
up from the lower faculties, then has this madness been the parent
of all those mighty revolutions that have happened in empire, in
philosophy, and in religion. For the brain in its natural position
and state of serenity disposeth its owner to pass his life in the
common forms, without any thought of subduing multitudes to his own
power, his reasons, or his visions, and the more he shapes his
understanding by the pattern of human learning, the less he is
inclined to form parties after his particular notions, because that
instructs him in his private infirmities, as well as in the stubborn
ignorance of the people. But when a man's fancy gets astride on his
reason, when imagination is at cuffs with the senses, and common
understanding as well as common sense is kicked out of doors, the
first proselyte he makes is himself; and when that is once
compassed, the difficulty is not so great in bringing over others, a