If you have a dog, you know that a dog is pretty useless for anything practical. Basically it eats drinks, pees and defecates, and then spends most of the rest of the time just sort of napping.
Which means that from a certain perspective a dog is useless. It doesn’t do the dishes, take out the trash, help the kids with their homework, or anything else really.
Yet all across the world, many millions of people have dogs. From this we can conclude the following with certainty: Whatever it is that dogs do, it is clearly incredibly important.
Ironically, the clearer the evidence that dogs are useless, the more obvious it becomes that they are vitally useful.