Certain it is that we know best what we are least conscious of
knowing, or at any rate least able to prove, as, for example, our own
existence, or that there is a country England. If any one asks us
for proof on matters of this sort, we have none ready, and are justly
annoyed at being called to consider what we regard as settled
questions. Again, there is hardly anything which so much affects our
actions as the centre of the earth (unless, perhaps, it be that still
hotter and more unprofitable spot the centre of the universe), for we
are incessantly trying to get as near it as circumstances will allow,
or to avoid getting nearer than is for the time being convenient.
Walking, running, standing, sitting, lying, waking, or sleeping, from
birth till death it is a paramount object with us; even after death--
if it be not fanciful to say so--it is one of the few things of which
what is left of us can still feel the influence; yet what can engross
less of our attention than this dark and distant spot so many
thousands of miles away?

The air we breathe, so long as it is neither too hot nor cold, nor
rough, nor full of smoke--that is to say, so long as it is in that
state within which we are best acquainted--seldom enters into our
thoughts; yet there is hardly anything with which we are more
incessantly occupied night and day.

Indeed, it is not too much to say that we have no really profound
knowledge upon any subject--no knowledge on the strength of which we
are ready to act at all moments unhesitatingly without either
preparation or after-thought--till we have left off feeling conscious
of the possession of such knowledge, and of the grounds on which it
rests. A lesson thoroughly learned must be like the air which feels