remember, that when the headache begins the reading or the thinking
must stop. As you value tho long and unimpaired preservation of your
powers of mind, guard carefully against any over-exertion of them.

To return to the "Analogy." It is a book of which you cannot too soon
begin the study,--providing you, as it will do, at once with materials
for the deepest thought, and laying a safe foundation for all future
ethical studies; it is at the same time so clearly expressed, that you
will have no perplexity in puzzling out the mere external form of the
idea, instead of fixing all your attention on solving the difficulties
of the thoughts and arguments themselves. Locke on the Human
Understanding is a work that has probably been often recommended to you.
Perhaps, if you keep steadily in view the danger of his materialistic,
unpoetic, and therefore untrue philosophy, the book may do you more good
than harm; it will furnish you with useful exercise for your thinking
powers; and you will see it so often quoted as authority, on one side as
truth, on the other as falsehood, that it may be as well you should form
your own judgment of it. You should previously, however, become guarded
against any dangers that might result from your study of Locke, by
acquiring a thorough-knowledge of the philosophy of Coleridge. This will
so approve itself to your conscience, your intellect, and your
imagination, that there can be no risk of its being ever supplanted in a
mind like yours by "plebeian"[79] systems of philosophy. Few have now
any difficulty in perceiving the infidel tendencies of that of Locke,
especially with the assistance of his French philosophic followers,
(with whose writings, for the charms of style and thought, you will
probably become acquainted in future years.) They have declared what the
real meaning of his system is by the developments which they have proved
to be its necessary consequences. Let Coleridge, then, be your previous
study, and the philosophic system detailed in his various writings may
serve as a nucleus, round which all other philosophy may safely enfold
itself. The writings of Coleridge form an era in the history of the
mind; and their progress in altering the whole character of thought, not
only in this but in foreign nations, if it has been slow, (which is one
of the necessary conditions of permanence,) has been already
astonishingly extensive. Even those who have never heard of the name of
Coleridge fin