it be true that every one is bound to promote to the extent of his ability
the good of others, and that to be useful to no one is really to be
worthless, yet it is likewise true that our cares ought to extend beyond
the present, and it is good to omit doing what might perhaps bring some
profit to the living, when we have in view the accomplishment of other
ends that will be of much greater advantage to posterity. And in truth, I
am quite willing it should be known that the little I have hitherto
learned is almost nothing in comparison with that of which I am ignorant,
and to the knowledge of which I do not despair of being able to attain;
for it is much the same with those who gradually discover truth in the
sciences, as with those who when growing rich find less difficulty in
making great acquisitions, than they formerly experienced when poor in
making acquisitions of much smaller amount. Or they may be compared to the
commanders of armies, whose forces usually increase in proportion to their
victories, and who need greater prudence to keep together the residue of
their troops after a defeat than after a victory to take towns and
provinces. For he truly engages in battle who endeavors to surmount all
the difficulties and errors which prevent him from reaching the knowledge
of truth, and he is overcome in fight who admits a false opinion touching
a matter of any generality and importance, and he requires thereafter much
more skill to recover his former position than to make great advances when
once in possession of thoroughly ascertained principles. As for myself, if
I have succeeded in discovering any truths in the sciences (and I trust
that what is contained in this volume 1 will show that I have found some),
I can declare that they are but the consequences and results of five or
six principal difficulties which I have surmounted, and my encounters with
which I reckoned as battles in which victory declared for me. I will not
hesitate even to avow my belief that nothing further is wanting to enable
me fully to realize my designs than to gain two or three similar
victories; and that I am not so far advanced in years but that, according