Anyone who trains animals recognizes that human and animal perceptual capacities are different. For most humans, seeing is believing, although we do occasionally brood about whether we can believe our eyes. The other senses are largely ancillary; most of us do not know how we might go about either doubting or believing our noses. But for dogs, scenting is believing. A dog's nose is to ours as the wrinkled surface of our complex brain is to the surface of an egg. A dog who did comparative psychology might easily worry about our consciousness or lack thereof, just as we worry about the consciousness of a squid.

We who take sight for granted can draw pictures of scent, but we have no language for doing it the other way about, no way to represent something visually familiar by means of actual scent. Most humans cannot know, with their limited noses, what they can imagine about being deaf, blind, mute, or paralyzed. The sighted can, for example, speak of a blind person as "in the darkness", but there is no corollary expression for what it is that we are in relationship to scent. If we tried to coin words, we might come up with something like "scent-blind". But what would it mean? It couldn't have the sort of meaning that "color-blind" and "tone-deaf' do, because most of us have experienced what "tone" and "color" mean in those expressions, but we don't know what "scent" means in the expression "scent-blind". Scent for many of us can be only a theoretical, technical expression that we use because our grammar requires that we have a noun to go in the sentences we are prompted to utter about animals tracking. We don't have a sense of scent. What we do have is a sense of smell—for Thanksgiving dinner and skunks and a number of things we call chemicals. So if Fido and I are sitting on the terrace, admiring the view, we inhabit worlds with radically different principles of phenomenology. Say that the wind is to our backs. Our world lies all before us, within a 180-degree angle. The dog's-well, we don't know, do we?

He sees roughly the same thing that I see but he believes the scents of the garden behind us. He marks the path of the black-and-white cat as she moves among the roses in search of the bits of chicken sandwich I let fall as I walked from the house to our picnic spot. I can show that Fido is alert to the kitty, but not how, for my picture-making modes of thought too easily supply falsifyingly literal representations of the cat and the garden and their modes of being hidden from or revealed to me.