28 PRESIDENT’S ADDRESS. 
Professor Strutt has shown that the amount of neon in 1/20 of 
a cubic centimetre of the air at ordinary pressures can be detected 
by the spectroscope ; Sir William Ramsay estimates that the neon 
in the air only amounts to one part of neon in 100,000 parts of 
air, so that the neon in 1/20 of a cubic centimetre of air would 
only occupy at atmospheric pressure a volume of half a millionth 
of a cubic centimetre. When stated in this form the quantity 
seems exceedingly small, but in this small volume there are about 
ten million million molecules. Now the population of the earth 
is estimated at about fifteen hundred millions, so that the smallest 
number of molecules of neon we can identify is about 7,000 times 
the population of the earth. In other words, if we had no better 
test for the existence of a man than we have for that of an 
unelectrified molecule we should come to the conclusion that the 
earth is uninhabited.’ 
The parable is a striking one, for on these lines it might legitimately 
be contended that we have no right to say positively that even space 
is uninhabited. All we can safely say is that we have no means of 
detecting the existence of non-planetary immaterial dwellers, and that 
unless they have some link or bond with the material they must always 
be physically beyond our ken. We may therefore for practical purposes 
legitimately treat them as non-existent until such link is discovered, 
but we should not dogmatise about them. ‘True agnosticism is legiti- 
mate, but not the dogmatic and positive and gnostic variety. 
For I hold that Science is incompetent to make comprehensive 
denials, even about the Ether, and that it goes wrong when it makes 
the attempt. Science should not deal in negations: it is strong in 
affirmations, but nothing based on abstraction ought to presume to 
deny outside its own region. It often happens that things abstracted 
from and ignored by one branch of science may be taken into con- 
sideration by another :— 
Thus, Chemists ignore the Ether. 
Mathematicians may ignore experimental difficulties. 
Physicists ignore and exclude live things. 
Biologists exclude Mind and Design. 
Psychologists may ignore human origin and human destiny. 
Folk-lore students and comparative Mythologists need not trouble 
about what modicum of truth there may be in the legends which they 
are collecting and systematising. 
And Microscopists may ignore the stars. 
Yet none of these ignored things should be denied. 
Denial is no more infallible than assertion. There are cheap and 
