A little higher in the animal world a rude ear has developed, first as a very delicate organ for feeling the waves caused by approaching food or enemies; only later as an organ of hearing. Meanwhile the eye has been developing, to perceive the subtle ether vibrations. The eye of the turbellaria distinguishes only light from darkness, that of the annelid is a true visual organ. Now the brain can begin to perceive the shape of objects at a little distance. Touch and smell, hearing, sight; such is sequence of sense perceptions. The sense-organs respond to continually more delicate and subtle impacts, and cover an ever-widening range of more and more distant objects. Up to this point intelligence has hardly included more than sense-perceptions.

But these sense-perceptions have been all the time spurring the mind to begin a higher work. At first it is conscious merely of objects, and its main effort is to gain a clearer and clearer perception of these.

Now it is led to undertake, so to speak, the work of a sense-organ of a higher grade. It begins to directly see invisible relations just as truly as through the eye it has perceived light. First perhaps it perceives that certain perceptions and experiences, agreeable or disagreeable, occur in a certain sequence. It begins to associate these. It learns thus to recognize the premonitory symptoms of nature's favor or disfavor, and thus gains food or avoids dangers. The bee learns to associate accessible nectar with a certain spot on the flower marked by bright dots or lines, "honey-guides," and the chimpanzee that when a hen cackles there is an egg in the nest. But association is only the first lesson; inference and understanding follow.

The child at kindergarten receives a few blocks. It admires and plays with them. Then it is taught to notice their form. After a time it arranges them in groups and learns the first elements of number. But when it has advanced to higher mathematics, the blocks, or figures on the blackboard, become only symbols or means of illustrating the great theorems and propositions of that science. Thus the animal has begun in the kindergarten way to dimly perceive that there are real, though intangible and invisible, relations between objects. But what is all human science but the clearer vision, and farther search into, and tracing of these same relations? And what is all advance of knowledge but a perception of ever subtler relations? What is even the knowledge of right but the perception of the subtlest and deepest and widest relations of man to his environment? The animal seems to be steadily advancing along the path toward the perception of abstract truth, though man alone really attains it.

And the higher power of association and inference which we call understanding, aided by memory, results in the power of learning by experience, so characteristic of higher vertebrates. The hunted bird or mammal very quickly becomes wary. A new trap catches more than a better old one until the animals have learned to understand it, and young animals are trapped more easily than old. Cases showing the limitations of mammalian intelligence are interesting in this connection. A cat which wished to look out and find the cause of a noise outside, when all the windows were closed by wooden blinds, jumped upon a stand and looked into a mirror. Her inference as to the general use of glass was correct; all its uses had not yet come

within the range of her experience. A monkey used to stop a hole in the side of a cage with straw. The keeper, to tease him, used to pull this out. But one day the monkey tugged at a nail in the side of his cage until he had pulled it out, and thrust it into the hole. But when it was pushed back he fell into a rage. His inference that the nail-head could not be pulled through was entirely correct; he had failed to foresee that it could be pushed back. Many such instances have probably come within the range of your observation, if you have noticed them. But many of the facts which Mr. Romanes gives us concerning the intelligence of monkeys, apes, and baboons would not disgrace the intelligence of children or men.

Mr. Romanes relates the following account of a little capuchin monkey from Brazil:

"To-day he obtained possession of a hearth-brush, one of the kind which has the handle screwed into the brush. He soon found the way to unscrew the handle, and having done that he immediately began to try to find out the way to screw it in again. This he in time accomplished. At first he put the wrong end of the handle into the hole, but turned it round and round the right way for screwing. Finding it did not hold he turned the other end of the handle and carefully stuck it into the hole, and began again to turn it the right way. It was of course a difficult feat for him to perform, for he required both his hands in order to screw it in, and the long bristles of the brush prevented it from remaining steady or with the right side up. He held the brush with his hind hand, but even so it was very difficult for him to get the first turn of the screw to fit into the thread; he worked at it, however, with the most unwearying perseverance until he got the first turn of the screw to catch, and he then quickly turned it round and round until it was screwed up to the end. The most remarkable thing was, that however often he was disappointed in the beginning, he never

was induced to try turning the handle the wrong way; he always screwed it from right to left. As soon as he had accomplished his wish he unscrewed it again, and then screwed it in again the second time rather more easily than the first, and so on many times. When he had become by practice tolerably perfect in screwing and unscrewing, he gave it up and took to some other amusement. One remarkable thing is that he should take so much trouble to do that which is no material benefit to him. The desire to accomplish a chosen task seems a sufficient inducement to lead him to take any amount of trouble. This seems a very human feeling, such as is not shown, I believe, by any other animal. It is not the desire of praise, as he never notices people looking on; it is simply the desire to achieve an object for the sake of achieving an object, and he never rests nor allows his attention to be distracted until it is done.

"As my sister once observed while we were watching him conducting some of his researches, in oblivion to his food and all his other surroundings-'When a monkey behaves like this it is no wonder that man is a scientific animal!'"*

In the highest mammals we find also different degrees of attention and concentration of thought and observation. This difference can easily be noticed in young hunting dogs. A trainer of monkeys said that he could easily select those which could most easily be taught, by noticing in the first lesson whether he could easily gain and hold their attention. This was easy with some, while others were diverted by every passing fly; and the latter, like heedless students, made but slow progress.

It is interesting to notice that one of the perceptions which we class among the highest is apparently developed comparatively early. I refer to the æsthetic perception of the beautiful. Now, the perception of beauty is generally considered as not very far below or *Romanes: Animal Intelligence, pp. 490, 498.

removed from the perception of truth and right. But some insects and birds apparently possess this perception and the corresponding emotion in no low degree. The colors of flowers seem to exist mainly for the attraction of insects to insure cross-fertilization, and certain insects seem to prefer certain colors. But you may say that these afford merely sense gratification like that which green affords to our eyes or sugar to our tastes.

But does not the grouping of colors in the flower appeal to some aesthetic standard in the mind of the insect? What of the tail of the peacock? Its iridescent rings and eyes evidently appeal to something in the mind of the female. Do form and grouping minister to pure sense gratification? What of the song of the thrush? Does not the orderly and harmonious arrangement of notes and cadences appeal to some standard of order of arrangement, and hence idea of harmony, in the mind of the bird's mate?

Now, I grant you readily that the A B C of this training is mere sense gratification at the sight of bright colors. Most insects and birds have probably not advanced much beyond this first lesson. Savages have generally stopped there or reverted to it. But any appreciation of form and harmonious arrangement of cadence and colors seems to me at least to demand some perception which we must call æsthetic, or dangerously near it. But here you must judge carefully for yourselves lest you be misled. For remember, please, that those schemes of psychology farthest removed from, and least readily reconcilable to, the theory of evolution maintain that perception of beauty is the work of the rational faculty, which also perceives truth