that our basis of Facts is sufficient for our purpose, and hence the
_possibility_ of error always exists.

It is not to be understood, therefore, that first or observational
_Facts_ are not rightly to be known in other departments of
investigation than Mathematics, Astronomy, and Physics; but that Laws,
Principles, or Generalizations which _relate_ Facts and serve as
instruments for penetrating into the deeper arcana of Nature, cannot be
precisely, accurately, and certainly _known_, in their relations and
belongings, until we are able to establish their connection with the
lowest, most fundamental, and self-evident truths, and in this manner
become competent to advance step by step from undeniable first truths to
those equally undeniable. In Mathematics, in Astronomy, and in Physics,
we are able to do this. We _know_ the Laws or Principles of these
Sciences, therefore, so far as we have developed the Sciences
themselves. We know the relations of the various Laws within the range
of each Science, and the relations of the different Sciences with each
other. We can advance, within their boundaries, from the simplest and
most positive verities, such as the whole is equal to all its parts--a
self-evident truth, which it is impossible to conceive as being
otherwise than as here stated--up to the most intricate ulterior Facts
of the universe, by Inferences which are as irresistible to the mind as
the axioms with which we started. In no other domains of Thought can
this be done by any methods now in vogue. In no other realms, therefore,
are complete precision and infallibility attainable. It is this which
constitutes the peculiar character of these three Sciences, and
distinguishes them radically from all others.

The whole body of our authoritative and irrevocably determinate
intellectual acquisitions lies, therefore, at the present time, so far