256 Luck, or Cunning ? 
possible modes of action very evenly balanced as regards 
advantage and disadvantages, then the ultimate appear- 
ance of two corresponding forms of life is a sequitur from 
the admission that form varies as function, and function as 
opinion concerning advantage. If there are three, four, 
five, or six such opinions tenable, we ought to have three, 
four, five, or six main subdivisions of life. As things are, 
we have two only. Can we, then, see a matter on which 
opinion was likely to be easily and early divided into two, 
and only two, main divisions—no third course being con- 
ceivable ? If so, this should suggest itself as the probable 
source from which the two main forms of organic life have 
been derived. 
I submit that we can see such a matter in the question 
whether it pays better to sit still and make the best of 
what comes in one’s way, or to go about in search of what 
one can find. Of course we, as animals, naturally hold that 
it is better to go about in search of what we can find than 
to sit still and make the best of what comes; but there 
is still so much to be said on the other side, that many 
classes of animals have settled down into sessile habits, 
while a perhaps even larger number are, like spiders, 
habitual liers in wait rather than travellers in search of 
food. I would ask my reader, therefore, to see the opinion 
that it is better to go in search of prey as formulated, and 
finding its organic expression, in animals; and the other— 
that it is better to be ever on the look-out to make the best 
of what chance brings up to them—in plants. Some few 
intermediate forms still record to us the long struggle 
during which the schism was not yet complete, and the 
halting between two opinions which it might be expected 
that some organisms should exhibit. 
“Neither class,’ I said in ‘“ Alps and Sanctuaries,” 
“has been quite consistent. Who ever is or can be? 
Every extreme—every opinion carried to its logical end— 
will prove to be an absurdity. Plants throw out roots and 
