Thus the more closely we can confine our data for 
     reasoning about things to data that come to us through 
     one and the same sense channel the more apt we are to 
     be correct in our reasoning, even though it be much more 
     restricted in its scope. One of the most interesting things 
     in our modern scientific practice has been the invention 
     and perfection of methods by which the scientists can 
     acquire much of their basic data through one and the 
     same sensuous channel of awareness. I understand that 
     in physics, for example, the scientists are happiest when 
     they can get their data with the aid of some dial or other 
     device which can be read by vision. Thus heat, weight, 
     lengths, and many other things that in ordinary life are 
     apprehended through senses other than vision have 
     become for science matters of visual awareness of the 
     positions of mechanical pointers.