Now, this sense of the presence of other living beings is very well developed in the lower animals, particularly in those whose safety depends upon the knowledge of the presence of their natural enemies.  As might be expected, the wild animals have it more highly developed than do the domesticated animals.  But even among the latter, we find instances of this sense being in active use—­in the case of dogs, horses, geese, etc., especially.  Who of us is not familiar with the strange actions of the dog, or the horse, when the animal senses the unseen and unheard presence of some person or animal?  Very often we would scold or punish the animal for its peculiar actions, simply because we are not able to see what is worrying it.  How often does the dog start suddenly, and bristle up its hair, when nothing is in sight, or within hearing distance.  How often does the horse grow “skittish,” or even panicky, when there is nothing within sight or hearing.  Domestic fowls, especially geese, manifest an uneasiness at the presence of strange persons or animals, though they may not be able to see or hear them.  It is a matter of history that this sense, in a flock of geese, once saved ancient Rome from an attack of the enemy.  The night was dark and stormy, and the trained eyesight and keen hearing of the Roman outposts failed to reveal the approach of the enemy.  But, the keen sense of the geese felt the presence of strange men, and they started to cackle loudly, aroused the guard, and Rome was saved.  Skeptical persons have sought to explain this historical case by the theory that the geese heard the approaching enemy.  But this explanation will not serve, for the Roman soldiers were marching about on their posts and guard-duty, and the geese remained silent until they sensed the approach of the small number of the enemy’s scouts, when they burst into wild cries.  The ancient Romans, themselves, were under no illusion about the matter—­they recognized the existence of some unusual power in the geese, and they gave the animals the full credit therefor.

Hunters in wild and strange lands have told us that often when they were lying concealed for the purpose of shooting the wild animals when they came within range, they have witnessed instances of the existence of this strange faculty in the wild beasts.  Though they could not see the concealed hunters, nor smell them (as the wind was in the other direction) all of a sudden one or more of the animals (generally an old female) would start suddenly, and a shiver would be seen to pass over its body; then it would utter a low warning note, and away would fly the pack.  Nearly every hunter has had the experience of watching his expected game, when all of a sudden it would start off with a nervous jerk, and without waiting to sniff the air, as is usual, would bolt precipitately from the scene.  Moreover, many beasts of prey are known to sense the presence of their natural prey, even when the wind is in the other direction, and there is no sound or movement made by the crouching, fearstricken animal.  Certain birds seem to sense the presence of particular worms upon which they feed, though the latter be buried several inches in the earth, or in the bark of trees.