Even among the cat's remarkable collection of unique attributes, the purr stands alone. It is singular, personal, distinctive true feline performance art. The mysterious, uncannily soothing vibration, sometimes felt but not heard, other times rafter rattling, is at once eminently practical and one of nature's glorious luxuries. As both quintessentially feline self- expression and an admirably versatile communicative device, the purr is unequaled. Yet the purr remains a mystery.
Some books devoted to feline nature and behavior fail to even mention the purr.
The cat, whose bond with humanity is both ancient and extraordinarily intimate, seems determined to keep some of its secrets tucked away - probably right behind its purr box. It is a secret that has endured from the very beginning of the time of cats and will never be revealed. No one is entirely sure how a cat purrs. An obvious problem is that by the time an investigator gets in to search out the mechanism, the cat has stopped purring. Science offers three principal theories, none universally accepted.