'58 
A. D. Darbishire. 
The statement, with regard to any set of opinions, that 
we know what they are, but know not what they may be, can only 
be made by those who cannot see, or are too lazy to face, the real 
truth; which is that we know not what they are until we know 
what they have been and that it is only when we thus know what they 
are, that we are in a position to know what they may be. 
The history of the study of inheritance may be divided into 
three periods, which roughly correspond with the end of the 18th, 
the latter half (if not the whole) of the 19th, and the beginning of 
the 20th centuries. Speculation in the first period, started off on 
a track which was remarkably like that which we now follow and 
consider to be the right one; it went astray during the second 
period and the stagnation which characterizes that period is due to 
the misapprehension of the nature of the problem, which prevailed 
during it. The third period is characterized by a return to the path 
which, we believe, will lead us, and indeed, in great part, already 
has led us, to an understanding of the nature, and ultimately to 
a solution, of the problem. 
The First Period. 
The saying that a little knowledge is a dangerous thing is a 
very profound one, and is illustrated in a remarkable way by the 
history of the attempts to deal with the problem of inheritance. 
Thus, for a man coming to close quarters with a natural problem it 
is better that he should either know hardly anything at all about 
it or a very great deal; what is almost certain to be fatal to a 
successful grappling with the problem is an intermediate amount of 
knowledge. If he knows hardly anything at all, it is possible or 
even likely that, if he is keenly perceptive, he may get a general 
conspectus of the most salient features of the problem which will 
lead him to an interpretation of it, which is not far from the truth. 
But if he knows more than this, through having paid close attention 
to one feature, the knowledge which he has looms too large in pro¬ 
portion to its value, and is dust in his eyes which prevents him 
from obtaining the general conspectus. Suppose there are twelve 
essential features of the problem ; it is better to see each one 
dimly, than to see two so brightly that the rest are in darkness. 
(Best of all, of course, is to see all brightly. But this is very 
rarely attained to). Thus it is that the poetical imagination of 
Erasmus Darwin perceived the problem of inheritance in the same 
