T 2.2.12.4

Love in beasts is not caus'd so much by relation, as in our species; and that because their thoughts are not so active as to trace relations, except in very obvious instances. Yet 'tis easy to remark, that on some occasions it has a considerable influence upon them. Thus acquaintance, which has the same effect as relation, always produces love in animals either to men or to each other. For the same reason |any likeness among them is the source of affection. An ox confin'd to a park with horses, will naturally join their company, if I may so speak, but always leaves it to enjoy that of his own species, where he has the choice of both.