ultimate springs and principles are totally shut up from human
curiosity and enquiry. Elasticity, gravity, cohesion of parts,
communication of motion by impulse; these are probably the ultimate
causes and principles which we shall ever discover in nature; and we
may esteem ourselves sufficiently happy, if, by accurate enquiry and
reasoning, we can trace up the particular phenomena to, or near to,
these general principles. The most perfect philosophy of the natural
kind only staves off our ignorance a little longer: as perhaps the
most perfect philosophy of the moral or metaphysical kind serves
only to discover larger portions of it. Thus the observation of
human blindness and weakness is the result of all philosophy, and
meets us at every turn, in spite of our endeavours to elude or avoid
it.

  27. Nor is geometry, when taken into the assistance of natural
philosophy, ever able to remedy this defect, or lead us into the
knowledge of ultimate causes, by all that accuracy of reasoning for
which it is so justly celebrated. Every part of mixed mathematics
proceeds upon the supposition that certain laws are established by
nature in her operations; and abstract reasonings are employed, either
to assist experience in the discovery of these laws, or to determine
their influence in particular instances, where it depends upon any
precise degree of distance and quantity. Thus, it is a law of
motion, discovered by experience, that the moment or force of any body
in motion is in the compound ratio or proportion of its solid contents
and its velocity; and consequently, that a small force may remove
the greatest obstacle or raise the greatest weight, if, by any
contrivance or machinery, we can increase the velocity of that
force, so as to make it an overmatch for its antagonist. Geometry
assists us in the application of this law, by giving us the just
dimensions of all the parts and figures which can enter into any
species of machine; but still the discovery of the law itself is owing
merely to experience, and all the abstract reasonings in the world
could never lead us one step towards the knowledge of it. When we
reason a priori, and consider merely any object or cause, as it
appears to the mind, independent of all observation, it never could
suggest to us the notion of any distinct object, such as its effect;
much less, show us the inseparable and inviolable connexion between
them. A man must be very sagacious who could discover by reasoning
that crystal is the effect of heat, and ice of cold, without being
previously acquainted with the operation of these qualities.

                               PART II.

  28. But we have not yet attained any tolerable satisfaction with
regard to the question first proposed. Each solution still gives
rise to a new question as difficult as the foregoing, and leads us
on to farther enquiries. When it is asked, What is the nature of all
our reasonings concerning matter of fact? the proper answer seems to
be, that they are founded on the relation of cause and effect. When
again it is asked, What is the foundation of all our reasonings and
conclusions concerning that relation? it may be replied in one word,
Experience. But if we still carry on our sifting humour, and ask, What
is the foundation of all conclusions from experience? this implies a
new question, which may be of more difficult solution and explication.
Philosophers, that give themselves airs of superior wisdom and
sufficiency, have a hard task when they encounter persons of
inquisitive dispositions, who push them from every corner to which
they retreat, and who are sure at last to bring them to some dangerous
dilemma. The best expedient to prevent this confusion, is to be modest
in our pretensions; and even to discover the difficulty ourselves
before it is objected to us. By this means, we may make a kind of
merit of our very ignorance.

  I shall content myself, in this section, with an easy task, and
shall pretend only to give a negative answer to the question here
proposed. I say then, that, even after we have experience of the
operations of cause and effect, our conclusions from that experience
are not founded on reasoning, or any process of the understanding.
This answer we must endeavour both to explain and to defend.

  29. It must certainly be allowed, that nature has kept us at a great
distance from all her secrets, and has afforded us only the
knowledge of a few superficial qualities of objects; while she
conceals from us those powers and principles on which the influence of
those objects entirely depends. Our senses inform us of the colour,
weight, and consistence of bread; but neither sense nor reason can
ever inform us of those qualities which fit it for the nourishment and
support of a human body. Sight or feeling conveys an idea of the
actual motion of bodies; but as to that wonderful force or power,
which would carry on a moving body for ever in a continued change of
place, and which bodies never lose but by communicating it to
others; of this we cannot form the most distant conception. But
notwithstanding this ignorance of natural powers* and principles, we
always presume, when we see like sensible qualities, that they have
like secret powers, and expect that effects, similar to those which we
have experienced, will follow from them. If a body of like colour
and consistence with that bread, which we have formerly eat, be
presented to us, we make no scruple of repeating the experiment, and
foresee, with certainty, like nourishment and support. Now this is a
process of the mind or thought, of which I would willingly know the
foundation. It is allowed on all hands that there is no known
connexion between the sensible qualities and the secret powers; and
consequently, that the mind is not led to form such a conclusion
concerning their constant and regular conjunction, by anything which
it knows of their nature. As to past Experience, it can be allowed
to give direct and certain information of those precise objects
only, and that precise period of time, which fell under its
cognizance: but why this experience should be extended to future
times, and to other objects, which for aught we know, may be only in