Hugging a purring cat is an experience like no other. The whole animal vibrates at the same frequency that causes rainbows and unicorns to generate spontaneously. Purring leaves little doubt that the lap-warming predators we love so much are wizard aliens sent to commandeer our couches, destroy our houseplants, and charm us out of as many treats as possible.
The most fascinating thing about purring: Science cannot fully explain it. Here are four unsolved mysteries about purring.