needs of the animal presenting it, the perfection is to be attributed to a God-given faculty of wisdom. This, I say, is the oldest theory of instinct, and I may add that until within the past twenty-five years it has been the only theory of instinct. I think, therefore, I ought to begin by explaining that this venerable and time-honored theory is a purely theological explanation of the ultimate source of instinct, and therefore can not be affected by any scientific theory as to the proximate causes. It is with such a theory alone that we shall here be concerned.
"When giants build, men must bring the stones." For the past eight or ten years I have been engaged in elaborating Mr. Darwin's theories in the domain of psychology, and I can not allude to my own work in this connection without expressing the deep obligations under which I lie to his ever-ready and ever-generous assistance—assistance rendered not only in the way of conversation and correspondence, but also by his kindness in making over to me all his unpublished manuscripts, together with the notes and clippings which he had been making for the past forty years in psychological matters. I have now gone carefully through all this material, and have published most of it in my work on "Mental Evolution in Animals." I allude to this work on the present occasion in order to observe that, as it has so recently come out, I shall feel myself entitled to assume that few have read it; and therefore I shall not cramp my remarks by seeking to avoid any of the facts or arguments therein contained.
As there are not many words within the compass of our language which have had their meanings less definitely fixed than the word "instinct," it is necessary that I should begin by clearly defining the sense in which I shall use it.
In general literature and conversation we usually find that instinct is antithetically opposed to reason, and this in such wise that, while the mental operations of the lower animals are termed instinctive, those of man are termed rational. This rough-and-ready attempt at psychological classification has descended to us from remote antiquity, and, like kindred attempts at zoölogical classification, is not a bad one so far as it goes. To divide the animal kingdom into beasts, fowls, fish, and creeping things, is a truly scientific classification as far as it goes, only it does not go far enough for the requirements of more careful observation; that is to say, it only recognizes the more obvious and sometimes only superficial differences, while it neglects the more hidden and usually more important resemblances. And to classify all the mental phenomena of animal life under the term "instinct," while reserving the term "reason" to designate a mental peculiarity distinctive of man, is to follow a similarly archaic method. It is quite true that instinct preponderates in animals, while reason preponderates in man. This obvious fact is what the world has always seen, just as it saw that flying appeared to be distinctive of birds, and creeping of
