ere is no question of importance, whose decision is not comprised in
the science of man; and there is none, which can be decided with any
certainty, before we become acquainted with that science. In pretending,
therefore, to explain the principles of human nature, we in effect
propose a compleat system of the sciences, built on a foundation almost
entirely new, and the only one upon which they can stand with any
security.

And as the science of man is the-only solid foundation for the other
sciences, so the only solid foundation we can give to this science
itself must be laid on experience and observation. It is no astonishing
reflection to consider, that the application of experimental philosophy
to moral subjects should come after that to natural at the distance of
above a whole century; since we find in fact, that there was about the
same interval betwixt the origins of these sciences; and that reckoning
from THALES to SOCRATES, the space of time is nearly equal to that
betwixt, my Lord Bacon and some late philosophers [Mr. Locke, my Lord
Shaftesbury, Dr. Mandeville, Mr. Hutchinson, Dr. Butler, etc.] in
England, who have begun to put the science of man on a new footing, and
have engaged the attention, and excited the curiosity of the public. So
true it is, that however other nations may rival us in poetry, and
excel us in some other agreeable arts, the improvements in reason and
philosophy can only be owing to a land of toleration and of liberty.

Nor ought we to think, that this latter improvement in the science of
man will do less honour to our native country than the former in natural
philosophy, but ought rather to esteem it a greater glory, upon account
of the greater importance of that science, as well as the necessity it
lay under of such a reformation. For to me it seems evident, that the
essence of the mind being equally unknown to us with that of external
bodies, it must be equally impossible to form any notion of its powers
and qualities otherwise than from careful and exact experiments, and the
observation of those particular effects, which result from its different
circumstances and situations. And though we must endeavour to render all
our principles as universal as possible, by tracing up our experiments
to the utmost, and explaining all effects from the simplest and fewest
causes, it is still certain we cannot go beyond experience; and any
hypothesis, that pretends to discover the ultimate original qu