The CAUSES of these passions are likewise much the same in beasts as in us, making a just allowance for our superior knowledge and understanding. Thus animals have little or no sense of virtue or vice; they quickly lose sight of the relations of blood; and are incapable of that of right and property: For which reason the causes of their pride and humility must lie solely in the body, and can never be placed either in the mind or external objects. But so far as regards the body, the same qualities cause pride in the animal as in the human kind; and it is on beauty, strength, swiftness or some other useful or agreeable quality that this passion is always founded. The next question is, whether, since those passions are the same, and arise from the same causes through the whole creation, the manner, in which the causes operate, be also the same. According to all rules of analogy, this is justly to be expected; and if we find upon trial, that the explication of these phaenomena, which we make use of in one species, will not apply to the rest, we may presume that that explication, however specious, is in reality without foundation. In order to decide this question, let us consider, that there is evidently the same relation of ideas, and derived from the same causes, in the minds of animals as in those of men. A dog, that has hid a bone, often forgets the place; but when brought to it, his thought passes easily to what he formerly concealed, by means of the contiguity, which produces a relation among his ideas. In like manner, when he has been heartily beat in any place, he will tremble on his approach to it, even though he discover no signs of any present danger. The effects of resemblance are not so remarkable; but as that relation makes a considerable ingredient in causation, of which all animals shew so evident a judgment, we may conclude that the three relations of resemblance, contiguity and causation operate in the same manner upon beasts as upon human creatures. There are also instances of the relation of impressions, sufficient to convince us, that there is an union of certain affections with each other in the inferior species of creatures as well as in the superior, and that their minds are frequently conveyed through a series of connected emotions. A dog, when elevated with joy, runs naturally into love and kindness, whether of his master or of the sex. In like manner, when full of pain and sorrow, he becomes quarrelsome and ill-natured; and that passion; which at first was grief, is by the smallest occasion converted into anger.