<p>The Alphabet of Ben Sira, a medieval text composed between 700 and 1000 CE, tells the longest and wildest origin story for why dogs and cats can't stand each other. It goes all the way back to Adam.</p>

<p>Originally, the cat and the dog were hunting partners. But food grew scarce. The dog proposed a split: the cat would go live with Adam and eat well indoors, while the dog would fend for himself in the wild. One condition - they swore an oath never to serve the same master. The cat agreed, moved into Adam's house, found mice to eat, and thrived. Adam was delighted: "God has sent me a great gift!"</p>

<p>The dog's luck was the opposite. He tried staying with the wolf, who sent him to fight off intruders and nearly got him killed. The monkey chased him away. He tried the sheep, but his barking led wolves straight to the flock - and they devoured the sheep. Homeless and desperate, the dog wandered from place to place until he finally came to Adam's door.</p>

<p>Adam took him in immediately. At midnight, the dog heard footsteps and alerted Adam, who grabbed a spear. Together, man and dog chased off the wild animals. "Come live with me," Adam said. "Eat my food and drink my water." It was the beginning of humanity's oldest partnership.</p>

<p>But when the cat saw the dog walk in, he was furious. "You broke our oath!" The dog tried to make peace: "I won't take your food, I won't come into your space." The cat refused to listen. The dog eventually fled to the house of Adam's son Seth. He kept trying to reconcile, but the cat never forgave him.</p>

<p>"The practice of the ancestors is the practice of the descendants," the text concludes, "whether among animals or people." A broken oath echoes forever.</p>