Take your dog with you to the butcher and watch

Take your dog with you to the butcher and watch how much he understands of the goings on when you purchase your meal. It is a great deal and even includes a keen sense of property which will make him snap at a stranger’s hand daring to come near the meat his master has obtained and which he will be allowed to carry home in his mouth. But when you have to tell him “Wait, doggy, I haven’t paid yet!” his understanding is at an end. The pieces of metal or paper which he watches you hand over, and which carry your scent, he knows, of course; he has seen them before. But their function as money lies outside the animal range. It is not related to our natural or physical being, but comprehensible only in our interrelations as human beings. It has reality in time and space, has the quality of a real occurrence taking place between me and the butcher and requiring a means of payment of material reality. The meaning of this action registers exclusively in our human minds and yet has definite reality outside it - a social reality, though, sharply contrasting with the natural realities accessible to my dog.”

Alfred Sohn-Rethel
Intellectual and Manual Labour: a Critique of Epistemology, 1977.