ich is the necessary presupposition of a
reorganised speculative physics. The general assimilation of space and
time which dominates the constructive thought can claim the independent
support of Minkowski from the side of science and also of succeeding
relativists, while on the side of philosophers it was, I believe, one
theme of Prof. Alexander's Gifford lectures delivered some few years ago
but not yet published. He also summarised his conclusions on this
question in a lecture to the Aristotelian Society in the July of 1918.
Since the publication of _An Enquiry concerning the Principles of
Natural Knowledge_ I have had the advantage of reading Mr C. D. Broad's
_Perception, Physics, and Reality_ [Camb. Univ. Press, 1914]. This
valuable book has assisted me in my discussion in Chapter II, though I
am unaware as to how far Mr Broad would assent to any of my arguments as
there stated.

It remains for me to thank the staff of the University Press, its
compositors, its proof-readers, its clerks, and its managing officials,
not only for the technical excellence of their work, but for the way
they have co-operated so as to secure my convenience.

A. N. W.

IMPERIAL COLLEGE OF SCIENCE
AND TECHNOLOGY.
_April_, 1920.

CONTENTS

CHAP. PAGE

I NATURE AND THOUGHT 1

II THEORIES OF THE BIFURCATION OF NATURE 26

III TIME 49

IV THE METHOD OF EXTENSIVE ABSTRACTION 74

V SPACE AND MOTION 99

VI CONGRUENCE 120

VII OBJECTS 143

VIII SUMMARY 164

IX THE ULTIMATE PHYSICAL CONCEPTS 185

NOTE: ON THE GREEK CONCEPT OF A POINT 197

NOTE: ON SIGNIFICANCE AND INFINITE EVENTS 197

INDEX 199

THE CONCEPT OF NATURE

CHAPTER I

NATURE AND THOUGHT

The subject-matter of the Tarner lectures is defined by the founder to
be 'the Philosophy of the Sciences and the Relations or Want of
Relations between the different Departments of Knowledge.' It is fitting
at the first lecture of this new foundation to dwell for a