Many naturalists are of opinion, that the animals which we commonly consider as mute, have the power of imparting their thoughts to one another. That they can express general sensations is very certain; every being that can utter sounds, has a different voice for pleasure and for pain. The hound informs his fellows when he scents his game; the hen calls her chickens to their food by her cluck, and drives them from danger by her scream.

  Birds have the greatest variety of notes; they have indeed a variety, which seems almost sufficient to make a speech adequate to the purposes of a life which is regulated by instinct, and can admit little change or improvement. To the cries of birds, curiosity or superstition has always been attentive; many have studied the language of the feathered tribes, and some have boasted that they understood it.

  The most skilful or most confident interpreters of the sylvan dialogues have been commonly found among the philosophers of the east, in a country where the calmness of the air, and the mildness of the seasons, allow the student to pass a great part of the year in groves and bowers. But what may be done in one place by peculiar opportunities, may be performed in another by peculiar diligence. A shepherd of Bohemia has, by long abode in the forests, enabled himself to understand the voice of birds; at least he relates with great confidence a story, of which the credibility is left to be considered by the learned.

  "As I was sitting," said he, "within a hollow rock, and watching my sheep that fed in the valley, I heard two vultures interchangeably crying on the summit of the cliff. Both voices were earnest and deliberate. My curiosity prevailed over my care of the flock; I climbed slowly and silently from crag to crag, concealed among the shrubs, till I found a cavity where I might sit and listen without suffering or giving disturbance.

  "I soon perceived that my labour would be well repaid; for an old vulture was sitting on a naked prominence, with her young about her, whom she was instructing in the arts of a vulture's life, and preparing, by the last lecture, for their final dismission to the mountains and the skies.

  " 'My children,' said the old vulture, 'you will the less want my instructions, because you have had my practice before your eyes; you have seen me snatch from the farm the household fowl, you have seen me seize the leveret in the bush, and the kid in the pasture; you know to fix your talons, and how to balance your flight when you are laden with your prey. But you remember the taste of more delicious food; I have often regaled you with the taste of man.' 'Tell us,' said the young vultures, 'where man may be found, and how he may be known; his flesh is surely the natural food of the vulture. Why have you never brought a man in your talons to the nest?' 'He is too bulky,' said the mother: 'when we find a man we can only tear away his flesh, and leave his bones upon the ground.' 'Since man is so big,' said the young ones, 'how do you kill him? You are afraid of the wolf and of the bear, by what power are vultures superior to man? is man more defenceless than a sheep?' 'We have not the strength of a man,' returned the mother, 'and I am sometimes in doubt whether we have the subtilty; and the vultures would seldom feed upon his flesh, had not nature, that devoted him to our uses, infused into him a strange ferocity, which I have never observed in any other being that feeds upon the earth. Two herds of men will often meet and shake the earth with noise, and fill the air with fire. When you hear noise and see fire, with flashes along the ground, hasten to the place with your swiftest wing, for men are surely destroying one another; you will then find the ground smoking with blood and covered with carcasses; of which many are dismembered and mangled for the convenience of the vulture.' 'But when men have killed their prey,' said the pupil, 'why do they not eat it? When the wolf has killed a sheep, he suffers not the vulture to touch it till he is satisfied himself. Is not man another kind of wolf?' 'Man,' said the mother, 'is the only beast who kills that which he does not devour, and this quality makes him so much a benefactor to our species.' 'If men kill our prey and lay it in our way,' said the young one, 'what need shall we have of labouring for ourselves?' 'Because man will, sometimes,' replied the mother, 'remain for a long time quiet in his den. The old vultures will tell you when you are to watch his motions. When you see men in great numbers moving close together, like a flock of storks, you may conclude that they are hunting, and that you will soon revel in human blood.' 'But still,' said the young one, 'I would gladly know the reason of this mutual slaughter. I could never kill what I could not eat.' 'My child,' said the mother, 'this is a question which I cannot answer, though I am reckoned the most subtle bird of the mountain. When I was young, I used frequently to visit the aerie of an old vulture, who dwelt upon the Carpathian rocks; he had made many observations; he knew the places that afforded prey round his habitation, as far in every direction as the strongest wing can fly between the rising and setting of the summer sun; he had fed year after year on the entrails of men. His opinion was, that men had only the appearance of animal life, being really vegetables with a power of motion; and that as the boughs of an oak are dashed together by the storm, that swine may fatten upon the falling acorns, so men are, by some unaccountable power, driven one against another, till they lose their motion, that vultures may be fed. Others think they have observed something of contrivance and policy among these mischievous beings; and those that hover more closely round them, pretend, that there is, in every herd, one that gives directions to the rest, and seems to be more eminently delighted with a wide carnage. What it is that entitles him to such pre-eminence we know not; he is seldom the biggest or the swiftest, but he shows by his eagerness and diligence that he is, more than any of the others, a friend to the vultures.' "