THE PRESIDENTIAL ADDRESS 15 
summed up in the crisp, snappy sentences beloved of scientific 
journalism, such as that materialism is dead, or that matter is no 
more. The situation is rather that both materialism and matter 
need to be redefined in the light of our new knowledge. When this 
has been done, the materialist must decide for himself whether the 
only kind of materialism which science now permits can be suitably 
labelled materialism, and whether what remains of matter should be 
labelled as matter or as something else; it is mainly a question 
of terminology. 
What remains is in any case very different from the full-blooded 
matter and the forbidding materialism of the Victorian scientist. 
His objective and material universe is proved to consist of little more 
than constructs of our own minds. To this extent, then, modern 
physics has moved in the direction of philosophic idealism. Mind 
and matter, if not proved to be of similar nature, are at least found 
to be ingredients of one single system. There is no longer room for 
the kind of dualism which has haunted philosophy since the days of 
Descartes. 
This brings us at once face to face with the fundamental difficulty 
which confronts every form of philosophical idealism. If the 
nature we study consists so largely of our own mental constructs, 
why do our many minds all construct one and the same nature ? 
Why, in brief, do we all see the same sun, moon and stars ? 
I would suggest that physics itself may provide a possible although 
very conjectural clue. The old particle-picture which lay within 
the limits of space and time, broke matter up into a crowd of distinct 
particles, and radiation into a shower of distinct photons. The 
newer and more accurate wave-picture, which transcends the frame- 
work of space and time, recombines the photons into a single beam 
of light, and the shower of parallel-moving electrons into a continuous 
electric current. Atomicity and division into individual existences 
are fundamental in the restricted space-time picture, but disappear 
in the wider, and as far as we know more truthful, picture which 
transcends space and time. In this, atomicity is replaced by what 
General Smuts would describe as ‘ holism ’—the photons are no 
longer distinct individuals each going its own way, but members of 
a single organisation or whole—a beam of light. ‘The same is true, 
mutatis mutandis, of the electrons of a parallel-moving shower. The 
biologists are beginning to tell us, although not very unanimously, 
that the same may be true of the cells of our bodies. And is it not 
conceivable that what is true of the objects perceived may be true 
also of the perceiving minds? When we view ourselves in space 
and time we are quite obviously distinct individuals ; when we pass 
beyond space and time we may perhaps form ingredients of a con- 
tinuous stream of life. It is only a step from this to a solution of 
