that experience
accumulates daily, and, therefore, that 'progress of the species,' _in
all senses_, is an obvious and necessary fact. There is something which
is true in this view, mixed with a great deal which is false. Material
knowledge, the physical and mechanical sciences, make their way from
step to step, from experiment to experiment, and each advance is secured
and made good, and cannot again be lost. One generation takes up the
general sum of experience where the last laid it down, adds to it what
it has the opportunity of adding, and leaves it with interest to the
next. The successive positions, as they are gained, require nothing for
the apprehension of them but an understanding ordinarily cultivated.
Prejudices have to be encountered, but prejudices of opinion merely, not
prejudices of conscience or prejudices of self-love, like those which
beset our progress in the science of morality. But in morals we enter
upon conditions wholly different--conditions in which age differs from
age, man differs from man, and even from himself, at different moments.
We all have experienced times when, as we say, we should not know
ourselves; some, when we fall below our average level; some, when we are
lifted above, and put on, as it were, a higher nature. At such intervals
as these last (unfortunately, with most of us, of rare occurrence), many
things become clear to us which before were hard sayings; propositions
become alive which, usually, are but dry words; our hearts seem purer,
our motives loftier; our purposes, what we are proud to acknowledge to
ourselves.

And, as man is unequal to himself, so is man to his neighbour, and
period to period. The entire method of action, the theories of human
life which in one era prevail universally, to the next are unpractical
and insane, as those of this next would have seemed mere baseness to the
first, if the first could have anticipated them. One epoch, we may
suppose, holds some 'greatest nobleness principle,' the other some
'greatest happiness principle;' and then their very systems of axioms
will contradict one another; their general conceptions and their
detailed interpretations, their rules, judgments, opinions, practices
will be in perpetual and endless collision. Our minds take shape from
our hearts, and the facts of moral experience do not teach their own
meaning, but submit to many readings according to the power of the eye
which we bring with us.

The want of a clear