There is no better illustration of the action of instinct as opposed to conscious intelligence than is afforded by the parasitic birds,--the cuckoo in Europe and the cowbird in this country,--birds that lay their eggs in the nests of other birds. Darwin speculates as to how this instinct came about, but whatever may have been its genesis, it is now a fixed habit among these birds. Moreover, the instinct of the blind young alien, a day or two after it is hatched, to throw or crowd its foster-brothers out of the nest is a strange and anomalous act, and is as untaught and unreasoned as anything in vegetable life. But when our yellow warbler, finding this strange egg of the cowbird in her nest, proceeds to bury it by putting another bottom in the nest and carrying up the sides to correspond, she shows something very much like sense and judgment, though of a clumsy kind. How much simpler and easier it would be to throw out the strange egg! I have known the cowbird herself to carry an egg from a nest in which she wished to deposit one of her own. Again, how stupid and ludicrous it seems on the part of the mother sparrow, or warbler, or vireo, when she goes about toiling desperately to satisfy the hunger of her big clamorous bantling of a cowbird, never suspecting that she has been imposed upon! Of course the line that divides man from the lower orders is not a straight line. It has many breaks and curves and deep indentations. The man-like apes, as it were, mark where the line rises up into the domain of man. Furthermore, the elephant and the dog, especially as we know them in domestication, encroach upon man's territory. Men are born with aptitudes for different things, but the art and the science of them all they have to learn; proficiency comes with practice. Man must learn to spin his web, to build his house, to sing his song, to know his food, to sail his craft, to find his way--things that the animals know "from the jump." The animal inherits its knowledge and its skill: man must acquire his by individual effort; all he inherits is capacity in varying degrees for these things. The animal does rational things without an exercise of reason. It is intelligent as nature is intelligent. It does not know that it knows, or how it knows, while man does. Man's knowledge is the light of his mind that shines on many and widely different objects, while the knowledge of animals cannot be symbolized by the term "light" at all. The animal acts blindly so far as any conscious individual illumination or act of judgment is concerned. It does the thing unwittingly, because it must. Confront it with a new condition, and it has no resources to meet that condition. The animal knows what necessity taught its progenitors, and it knows that only as a spontaneous impulse to do certain things.