NATURE OF INTERPRETATION. 51 
to the contrary, this presumption amounts almost to a cer- 
tainty ; no one in practice doubts it fora moment. It does not 
fall within the limits of this Paper, or within the ability of the 
author, to discuss the supposed nature of things in the back of 
beyond. Seeing, however, that there is at present no logical 
escape from the conclusion that there is a ‘ back of beyond ” 
in which things happen, and that some at least of those 
happenings correspond in some sort of way with our inter- 
pretation of them, we are tempted to ask whether there are 
any grounds for supposing that all the happenings in the 
unknown find expression in the material world, and if not, can 
we conceive of any reason why they should not ? 
To go back for a moment to the theory of light. Physicists 
interpret light as a certain kind of wave motion ina hypothetical 
ether, while physiologists tell us that light is sensation of 
which we are capable under certain conditions. Compounding 
these two statements together we arrive at the important con- 
clusion that there is a something which transmits vibratory 
motion, that this motion excites the sensitive layer of the 
retina, and is transmitted by the optic nerve to the brain, where- 
on the sensation of light is experienced. Investigations go to 
show that only a very limited number of these vibrations are 
capable of exciting the retina, and that the differences of 
velocity, &c., which exist within those small limits, produce in 
the brain the different colour sensations known to us. But 
on the authority of evidence it is asserted that there are 
wave vibrations of too high and too low a velocity to give us 
the sensations of light, that the number of them is in all 
probability enormous, as compared with the very few vibra- 
tions which affect our eyes. A very similar case is made out 
for the sensation of sound, only here the wave vibrations are 
transmitted through matter, not through ether, and are of a 
somewhat different nature. Further, we are told, again upon 
evidence, that all our sensations reach us through the medium 
of the nerves, and that the cause of sensation is in all cases 
primarily wave motion of one kind or another, always very 
limited in its range. Thus, to speak rather inaccurately, but 
in a way which will be readily understood, it may be said that 
there are sounds we never hear, tastes we never experience, 
