isition of new truth or in the conduct of life. Mental activity,
then, is a duty; for if we are bound to preserve life, by parity of
reason, we are bound to improve its quality and increase its quantity, and
this cannot be done unless the intellectual powers are strengthened by
diligent exercise, as well as nourished by the facts and truths which are
the raw material of wisdom.

The fit *objects of knowledge* vary indefinitely with one's condition in
life. Things in themselves trivial or evanescent may, under certain
circumstances, claim our careful attention and thorough cognizance. We
ought, on the one hand, to know all we can about matters concerning which
we must speak or act, and, on the other hand, to refrain from voluntarily
speaking or acting in matters of which we are ignorant. Thus our social
relations and our daily intercourse may render it incumbent on us to
obtain for current use a large amount of accurate knowledge which is not
worth our remembering. Then a man's profession, stated business, or usual
occupation opens a large field of knowledge, with which and with its
allied provinces it is his manifest duty to become conversant to his
utmost ability; for the genuineness and value of his work must be in a
great degree contingent on his intelligence. At the same time, every man
is bound to make his profession worthy of respect; in failing to do so, he
wrongs and injures the members of his profession collectively; and no
calling can obtain respect, if those who pursue it show themselves
uncultivated and ignorant. Thus far, then, should knowledge be extended on
grounds of practical utility. Beyond and above this range, there is an
unlimited realm of truth, the knowledge of which is inestimably precious
for the higher culture of the mind and character. In this realm, of which
only an infinitesimal portion can be conquered during an earthly lifetime,
there is no unfruitful region,--there is no department of nature, of
psychology, or of social science, through which the mind may not be
expanded, exalted, energized, led into more intimate relations with the
Supreme Intelligence, endowed with added power of beneficent agency.
While, therefore, knowledge of things as they are, and of their underlying
principles and laws, so far as we are able to acquire it, is not only a
privilege beyond all price, but an absolute duty, there are no moral
considerations which need direct or limit our choice of the themes of
research