sitting up at night an hour or two later than usual, or by not taking
regular exercise, or by eating of indigestible food, you will put it out
of your power to avoid being ill-tempered and disagreeable on the
following day, the failure is surely a moral one. That the immediate
causes of your ill-humour may be physical ones, does not at all affect
the matter, seeing that such causes are, in this case, completely under
your own control. From this it follows that it must be a duty to watch
carefully the effects produced on your temper by every habit of your
life. If you do not abandon such of these as produce undesirable
effects, you deserve to experience the consequences in the gradual
diminution of the respect and affection of those who surround you.

Should the habits producing irritation of temper be such as you cannot
abandon without loss or detriment to yourself or others, the object in
view will be equally attained by exercising a more vigilant self-control
while you are exposed to a dangerous influence. For instance, you have
often heard it remarked, and have perhaps observed in your own case,
that poetry and works of fiction excite and irritate the temper. You may
know some people who exhibit this influence so strongly that no one will
venture to make them a request or even to apply to them about necessary
business, while they are engaged in the perusal of any thing
interesting. I know more than one excellent person, who, in consequence
of observing the effect produced on their temper, by novels, &c., have
given up this style of reading altogether. So far as the sacrifice was
made from a conscientious motive, they doubtless have their reward. From
the consequences, however, I should be rather inclined to think that
they were in many cases not only mistaken in the nature of the
precautions they adopted, but also in their motives for adopting them.
Such persons too frequently seem to have no more control over their
temper when exposed to other and entirely inevitable temptations, than