“Surefooted as a goat” is an old cliché, but “surefooted as a cat” would be just as accurate, for cats have an extraordinary sense of balance, enabling them to walk on narrow ledges, tree branches, and so on. (They have an obvious advantage over goats: claws to help steady themselves.)
As it is in humans, balance is connected to the inner ear. The cat’s inner ear has an organ called the vestibular apparatus, which, working in conjunction with the eyes, gives the cat a perfect sense of his location in space. With the smallest movement, he will act reﬂexively to balance himself once again.