For cat persons, the eras of our lives can be demarcated by the eras of our cats’ lives. I lived through the Era of Frisky (a beautiful rascal with tuxedo markings); the Era of Buster aka Big Red (a ginger cat, ever-sweet except for biting the houseguests); the Era of Snuffy (also tuxedoed, the King of the Credenza); and the Era of Mother Kitty (gray) and Skippy (her half-Siamese kitten). Mother Kitty and Skippy were feral issue of canyon San Diego—fixed, tamed in a convoluted subplot lasting years, and ultimately moved to Seattle, where they lived out their lives, happily, it seemed, indoors.

Domestic cats (Felis catus) came to us via Egypt. There in North Africa a wildcat of the smaller African variety (Felis silvestris libyca) began hunting the mice and small rats that infested ancient Egyptian granaries. The Egyptians didn’t mind, not at all. The oldest remains of cats domesticated in Egypt, dating to about 4000 BCE, are very big kitties, probably tamed wildcats. They had 30-inch-long bodies and 12-inch-long tails.

Egyptians began to control the breeding of wildcats, choosing cats that were less vicious and less spooky. Thus evolved the domestic cat, which became distinct from the wildcat around 2000 BCE. Our housecats evolved very late and under the selective pressure of Homo sapiens.

Cats are carnivores. They have 19 pairs of chromosomes (we have 23). They caterwaul (yowl) when preparing to fight. They are nocturnal hunters that can see in the dark. Cat eyes have a layer of cells behind the retina (called tapetum lucidum) that reflects light back to the retina, improving night vision and making their eyes glow in the dark. Cat whiskers (vibrissae) are feelers, hypersensitive to touch, aiding nocturnal navigation. (Cats don’t go bump in the night.) They sleep for 16 hours a day. They do not retract but rather, extend their claws. (A claw retracted is a claw at rest, unactivated.) They shed their claw sheaths, which is what they are doing when they are “sharpening their claws” on your upholstered chair. Under the claw sheath is a new claw, fine and sharp.

Cats are fastidious. They autogroom (clean themselves) and allogroom (clean each other).

When a cat kneads your thighs it is “milk-kneading,” reverting to kitten behavior to bring on its dam’s milk. (You’re its surrogate mother.) Cats chew grass to ingest grass juice containing folic acid, essential to their production of hemoglobin.

When you return home to your cat, it comes up and rubs its mouth and body on your legs, then goes off and licks itself. This, according to Desmond Morris in Cat World: A Feline Encyclopedia, is a scent-exchange ritual. A cat has scent glands at the edge of its mouth and on the baldish spots below its ears. It’s getting its scent on you and then licking your scent all over itself.

Some 77 million domestic cats live in the United States. Feline predation on songbirds is serious—hundreds of millions of birds each year, according to estimates by the American Bird Conservancy. If we want birds we should take seriously the campaign to keep our cats indoors.

Growing up on the farm, we had many cats, many dogs, many cows, a few horrid geese, and a number of dumb sheep. My youngest sister, Liz, inventoried, communed with, and named our 25 or so barn cats. Her names recognized a cat’s superior dignity: Johanna Spyri (the human of that name authored the children’s book Heidi), Louisa May Alcott, William Shakespeare, Pussae (Latin for Puss). T. S. Eliot also knew how to name a cat: Grumbuskin, Growltiger, Griddlebone (Old Possum’s Book of Practical Cats). May Sarton had her Fur Person. But the most famous cat in history, surely, was Jeoffry. Jeoffry was memorialized by his servant, the poet Christopher Smart (1722-1771), who spent half his life in Mr. Potter’s Madhouse. “For I will consider my cat Jeoffry … ” the great poem begins, and continues for 74 lines.

A lot more could be said about cats. (There are hundreds of books on the subject.) I will spare you, except to salute the human who invented the cat door: Sir Isaac Newton.