case, and
content ourselves as a plain matter of fact with what is. _To experience
we refer as the only ground for all physical enquiry._ But before
experience itself can be used to advantage, there is one preliminary
step to make which depends wholly upon ourselves."

"It is the _absolute dismissal_ and clearing the mind _of all
prejudices_ from whatever source arising, and the determination to stand
or fall by the result of direct appeal to facts in the first instance,
and to strict logical deduction from them afterwards."

From extracts like these, from such men as Newton and Herschel, it can
at once be seen that experience, and experience alone, should be the
chief fountain from whence we draw all our data to form the bases of any
hypothesis or theory. If the hypothesis formed is contradicted by the
result of any present or future observation or experiment, then such
hypothesis will either become untenable, or must be so modified as to
take in the new fact furnished by that observation and experiment.

It is a _sine qua non_ of all true philosophy, that philosophy should
always agree with experience. To the extent that our Philosophy of
Nature fails to agree with our experience, or with the results of
observation and experiment, then to that extent it ceases to be
philosophy. It may be a hypothesis or even a theory, but certainly it is
not true Philosophy.

Now, in the elaboration and development of the theory as to the physical
cause of Gravitation, I can premise that nothing will be postulated or
supposed, unless such supposition can be directly verified by our own
observation and experiments.

Any theory or hypotheses that are contradicted by our own experience in
its widest form, will find no place in the development of this work.
Further, any present accepted theory in relation to any natural
phenomena, which is controverted by experiment, or observation, will be
rejected as untenable in the scheme of Natural Philosophy to be
submitted to the reader.

Whatever else the theory suggested may, or may not be, one thing it
certainly shall be, and that is, that it shall be strictly based upon
the Philosophical Rules as given by some of the greatest philosophers
the world has ever seen. I do not premise that the hypotheses advanced
will be strictly correct in every detail.

That would be to assume that my experience of all natural phenomena was
perfect. To the extent that our experience is limited, to that ex