230° THE PHILOSOPHY OF BIRDS NESTS, 
phenomena presented by their mode of builling their 
nests, when fairly compared with those exhibited by 
the great mass of mankind in building their houses, 
indicate no essential difference in the kind or nature 
of the mental faculties employed. If instinct means 
anything, it means the capacity to perform some com- 
plex act without teaching or experience. It implies 
innate ideas of a very definite kind, and, if established, 
would overthrow Mr. Mill’s sensationalism and all the 
modern philosophy of experience. That the existence 
of true instinct may be established in other cases is 
not impossible, but in the particular instance of birds’ 
nests, which is usually considered one of its strong- 
holds, I cannot find a particle of evidence to show the 
existence of anything beyond those lower reasoning 
and imitative powers, which animals are universally 
admitted to vossess, 
