Aristotle [ca. 350 BCE] (De animalibus, Book 9, 25.12): The nautilus is a polypus peculiar both in its nature and its actions; for it sails upon the surface of the sea, rising up from the depths of the waters. It is brought to the surface with its shell inverted, in order that it may go out more easily and navigate in an empty shell. When it reaches the surface, it turns its shell over. There is a membrane extended between two of its tentacula similar to the web feet of birds, except that theirs is thick and that of the nautilus thin and like a spider's web. This it uses for a sail when the wind blows, and it extends two of its tentacula for rudders. If alarmed, it fills its shell and sinks in the sea. No one has made any accurate observation on the production and growth of the shell. It appears not to originate in sexual intercourse, but to be produced like that of other conchylia, nor is it clear whether it can live when taken out of its shell. - [Cresswell translation, 1887]

Pliny the Elder [1st century CE] (Natural History, Book 9, 47): But among outstanding marvels is the the creature called the nautilus, called by others the pilot-fish. Lying on its back it comes to the surface of the sea, gradually raising itself up in such a way that by sending out all the water through a tube it so to speak unloads itself of bilge and sails easily. Afterwards it twists back its two foremost arms and spreads out between them a marvelously thin membrane, and with this serving as a sail in the breeze while it uses its other arms underneath it as oars, it steers itself with its tail between them as a rudder. So it proceeds across the deep mimicking the likeness of a fast cutter, if any alarm interrupts its voyage submerging itself by sucking in water. - [Rackham translation]

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Marine monsters 6.36): Nautilus is a monster of the sea, as Pliny says, the greatest among marine miracles. It comes to the top of the water and raising itself there, lets out all the water through its pipe to empty itself so that it can sail easily. Afterward, it twists its first two arms to extend a membrane of amazing thinness between them, with which membrane it sails on the free winds, and rows with the rest of the arms and uses its tail in the middle to control itself as with a rudder. If, however, fear intervenes, it drinks water to sink itself. - [Badke translation/paraphrase]