things to which psychology cannot help us in the least.

The science of psychology, and whatever science of general pedagogics
may be based on it, are in fact much like the science of war. Nothing is
simpler or more definite than the principles of either. In war, all you
have to do is to work your enemy into a position from which the natural
obstacles prevent him from escaping if he tries to; then to fall on him
in numbers superior to his own, at a moment when you have led him to
think you far away; and so, with a minimum of exposure of your own
troops, to hack his force to pieces, and take the remainder prisoners.
Just so, in teaching, you must simply work your pupil into such a state
of interest in what you are going to teach him that every other object
of attention is banished from his mind; then reveal it to him so
impressively that he will remember the occasion to his dying day; and
finally fill him with devouring curiosity to know what the next steps in
connection with the subject are. The principles being so plain, there
would be nothing but victories for the masters of the science, either on
the battlefield or in the schoolroom, if they did not both have to make
their application to an incalculable quantity in the shape of the mind
of their opponent. The mind of your own enemy, the pupil, is working
away from you as keenly and eagerly as is the mind of the commander on
the other side from the scientific general. Just what the respective
enemies want and think, and what they know and do not know, are as hard
things for the teacher as for the general to find out. Divination and
perception, not psychological pedagogics or theoretic strategy, are the
only helpers here.

But, if the use of psychological principles thus be negative rather than
positive, it does not follow that it may not be a great use, all the
same. It certainly narrows the path for experiments and trials. We know