Literally, a rabbit hole is what the animal digs for its home. The earliest written record of the phrase dates back to the 17th century. But the figurative rabbit hole begins with Lewis Carroll’s 1865 classic, Alice’s Adventures in Wonderland. In its opening chapter, “Down the Rabbit-Hole,” Alice follows the White Rabbit into his burrow, which transports her to the strange, surreal, and nonsensical world of Wonderland.Since then, Carroll’s rabbit hole has proved a popular and useful reference...