day we must still seek a true
understanding of what knowledge is--what are its powers and what also
are its limitations. Nor may we forget that other principle of
life--with which it is so quaintly contrasted in Lord Bacon's
translation of the Pauline aphorism--_Knowledge bloweth up, Charity
buildeth up._

_January 1915._

CONTENTS

PAGE
I

TIME AND PERIODICITY 11

II

THE ORIGIN OF PHYSICAL CONCEPTS 17

III

THE TWO TYPICAL THEORIES OF KNOWLEDGE 36

IV

THE DOCTRINE OF ENERGY 81

ESSAYS TOWARDS A
THEORY OF KNOWLEDGE

I

TIME AND PERIODICITY

We can measure Time in one way only--by counting repeated motions. Apart
from the operation of the physical Law of Periodicity we should have no
natural measures of Time. If that statement be true it follows that
apart from the operation of this law we could not attain to any
knowledge of Time.[11:1] Perhaps this latter proposition may not at
first be readily granted. Few, probably, would hesitate to admit that in
a condition in which our experience was a complete blank we should be
unable to acquire any knowledge of Time; but it may not be quite so
evident that in a condition in which experience consisted of a
multifarious _but never repeated_ succession of impressions the
Knowledge of Time would be equally awanting.[12:1] Yet so it is. The
operation of the Law of Periodicity is necessary to the measurement of
Time. It is by means, and only by means, of periodic pulsative movements
that we ever do or can measure Time. Now, apart from some sort of
measurement Time would be unknowable. A time which was neither long nor
short would be meaningless. The idea of unquantified Time cannot be
conceived or apprehended. Time to be known must be measured.

Periodicity, therefore, is essential to our Knowledge of Time. But
Nature amply supplies us with this necessary instrument. The Law of
Periodicity prevails widely throughout Nature. It absolutely dominates
Life.

The centre of animal vitality is to be found in the beating heart and
breathing lungs. Pulsation qualifies not merely the nutrient life but
the musculo-motor activity as well. Eating, Walking,--all our most
elementary movements are pulsatory. We wake and sleep, we grow weary and
rest. We are born and we die, we are young and grow old. All animal life
is determined by this Law.

P