ADD RES S.





  ALL true science is of slow growth. All true knowledge has
ever been, and, from its very nature, must ever continue to be
an attainment, more or less gradual and progressive, and more
or less difficult of acquisition. Often does even the most
elementary knowledge, or the simplest and plainest truth, seem
to us to have been late and tardily acquired or discovered, and
the world wonders how it could happen, that what is now such
manifest and beautiful and far-darting light, should have re-
mained so long obscure, or altogether hidden. This is true of
all subjects of investigation, though it is more .strictly and re-
markably so of some than of others. History can be written
only after it has been acted. Nations must have lived and died,
they must have played their parts on this stage of the world,
before their lives and deaths and doings can become the sub-
jects of recital and commentary. Great biographies must be
lived and acted before they can be recorded. And, furthermore,
it may be, that ages shall elapse after the annalist has registered
his facts, before their relations come to be fully understood, and
the chain, which runs through them all and binds them together,
is rendered visible and luminous by the light of philosophy.
  Especially is this the case with all knowledge which is the
result of experiment and observation. Through a slow, irregu-
larly moving and progressive process, have a1l the natural
sciences been obliged to pass. The very art'itsilf of bbserVa-