The obscurity that involves all metaphysical subjects appears
to me, in the same manner, peculiarly calculated to add to that
class of excitements which arise from the thirst of knowledge. It
is probable that man, while on earth, will never be able to
attain complete satisfaction on these subjects; but this is by no
means a reason that he should not engage in them. The darkness
that surrounds these interesting topics of human curiosity may be
intended to furnish endless motives to intellectual activity and
exertion. The constant effort to dispel this darkness, even if it
fail of success, invigorates and improves the thinking faculty.
If the subjects of human inquiry were once exhausted, mind would
probably stagnate; but the infinitely diversified forms and
operations of nature, together with the endless food for
speculation which metaphysical subjects offer, prevent the
possibility that such a period should ever arrive.

It is by no means one of the wisest sayings of Solomon that
'there is no new thing under the sun.' On the contrary, it is
probable that were the present system to continue for millions of
years, continual additions would be making to the mass of human
knowledge, and yet, perhaps, it may be a matter of doubt whether
what may be called the capacity of mind be in any marked and
decided manner increasing. A Socrates, a Plato, or an Aristotle,
however confessedly inferior in knowledge to the philosophers of
the present day, do not appear to have been much below them in
intellectual capacity. Intellect rises from a speck, continues in
vigour only for a certain period, and will not perhaps admit
while on earth of above a certain number of impressions. These
impressions may, indeed, be infinitely modified, and from these
various modifications, added probably to a difference in the