6 THE PRESIDENTIAL ADDRESS. 
Space-time, therefore, does not seem to exist for the quantum, at least 
not in its lower multiples. Nay, more: the very hitting of its mark 
presents another strange puzzle, which seems to defy the principles of 
causation and of the uniformity of nature, and to take us into the realm 
of chance and probability. The significant thing is that this strange 
quantum character of the universe is not the result of theory but is ap 
experimental fact well attested from several departments of physics. In 
spite of the strange Puck-like behaviour of the quantum, we should not 
lightly conclude, with some prominent physicists, that the universe has 
a skeleton in its cupboard in the shape of an irrational or chaotic factor. 
Our macroscopic concepts may not fit this ultra-microscopic world of the 
quantum. And our best hopes for the future are founded on the working 
out of a new system of concepts and laws suited to this new world that 
has swum into the ken of science. The rapid development of wave 
mechanics in the last four years seems to have brought us within sight of 
this ideal, and we are beginning to discern a new kind of order in the 
microscopic elements of the world, very different from any type of law 
hitherto imagined in science, but none the less a rational order capable of 
mathematical formulation. 
We may summarise these remarks by saying that the vastly improved 
technique of research has led to physical discoveries in recent years which 
have at last completely shattered the traditional commonsense view of 
the material world. A new space-time world has emerged which is 
essentially immaterial, and in which the old-time matter, and even the 
scientific mass, gravitation, and energy stand for no independent entities, . 
but can best be construed as configurations of space-time. And the 
discovery of the quantic properties of this world points to still more 
radical transformations which loom on the horizon of science. The 
complete recasting of many of our categories of experience and thought 
may ultimately be involved. 
From the brilliant discoveries of physical science we pass on to the 
advances in biological science which, although far less revolutionary, have 
been scarcely less important for our world-outlook. The most important 
biological discovery of the last century was the great fact of organic 
evolution ; and for this fact the space-time concept has at last come to 
provide the necessary physical basis. It is unnecessary for my purpose 
to canvass the claims and discuss the views represented by the great names 
of Lamarck, Darwin and Mendel, beyond saying that they represent a 
progressive advance in biological discovery, the end of which has by 
