Birds and animals probably think without knowing that they think; that is, they have not self-consciousness. Only man seems to be endowed with this faculty; he alone develops disinterested intelligence, intelligence that is not primarily concerned with his own safety and well-being but that looks abroad upon things.

The art of the bird is to conceal its nest both as to position and as to material, but now and then it is betrayed into weaving into its structure showy and bizarre bits of this or that, which give its secret away and which seem to violate all the traditions of its kind.

Fear, love, and hunger were the agents that developed the wits of the lower animals, as they were, of course, the prime factors in developing the intelligence of man.

John Burroughs Quotes