In this connection I may also say that the shape or colour of a tail is not everything. An observant eye may find much to note in the wearing of them. There is a stylish way of carrying a tail and a slovenly way, and there are coquettish arts for the display of recherche tails. A blackbird and a starling are both tidy birds, and both walk much on the ground, but the one lifts its skirts, while the other, more practical and less fashionable, wears a walking dress and saves itself trouble.
This line of observation leads to a higher, and reveals the most important purpose that tails have served in the economy of beast, bird, and reptile, and, perhaps, even cold-blooded fish. Before the godlike countenance of man appeared on the earth, with its contractile forehead and erectile eyebrows, the answering light of the eye, the expansive nostrils, and subtilely mobile lips; before that the tail was the prime vehicle of emotion and safety-valve of passion. It is a great truth, too often buried in these days under rubbish of materialistic theories, that some way of self-manifestation is a supreme necessity of all sentient life. From the hot centre of thought and feeling the currents rush along the nervous ways and pervade the whole frame, seeking an outlet. But many passages are barred by duty, or fear, or eager purpose. A strong gust of passion may burst all barriers and force its way out at every point, but gentle currents flow along the lines of least resistance and find the idle tail. I do not know a better illustration of this than a cat watching a mouse. The ears are pricked forward, the eyes are fixed on the unsuspecting victim, every muscle of the legs is tense, like a bent bow ready to speed the arrow on its way. But see, the excitement with which the whole body is charged cannot be wholly restrained, and oozes out at the point of the tail.
Every emotion and passion takes this course. The happy kid wags its tail as it runs to its mother, the donkey when it has executed a successful bray, and the dog when it sees its master. At the sight of a rival the dog holds its tail up stiffly, unless, indeed, the rival is a bigger dog than itself, in which case the index goes down quickly between the legs. An elated horse elevates its tail, and so does a duck in the same mood. A lizard preparing to fight another lizard
Swinges the scaly horror of his folded tail,
and the raging lion of fiction lashes its sides with the same nervous instrument.
It would be tedious to dwell on the pretty part which the tail plays in the courtships of sparrows and pigeons, or on the sprightly attitudes by which birds of all sorts let off their spirits when shower and sunshine have overfilled their hearts with gladness. But birds twitch their tails constantly, without meaning anything by it. The ceaseless wagging of a wagtail is a mere habit of cheerfulness, like the twirling of her thumbs by an idle Scotswoman. The long tail is there and something must be done with it. Look at the embarrassment which a nervous young man shows about the disposal of his hands; how he thrusts them into his trouser pockets, hangs them by their thumbs from the arm-holes of his waistcoat, or gives them a walking-stick to play with. I like to imagine what such a fellow would do with a long tail if he had it—how he would wind it round each leg in turn, rub up his back hair, and describe figures on the floor. But no animal so self-conscious as man could bear up long under the nervous strain of having to think continually of its tail. It would die young and the race would become extinct. Perhaps it did.