The Prose Edda
"Expression is of two kinds: that which is called voice, and that which is called manners; manners is also temper. Reiði also has double meaning: reiði is the ill humor of a man, and reiði is also the rigging of a ship or the driving-gear of a horse. Fár also has double meaning: fár signifies wrath, and far signifies a ship.
"Men have made frequent use of such ambiguous expressions as these; and this practice is called punning. [Lith is that part of a man where bones meet; lið is a word for ship; lið means people; when a man renders an other assistance, his aid is lið; líð signifies ale. Hlið signifies the gate in a garth; hliðr men call an ox, and hlíð signifies a slope. One may make such use of these distinct meanings in skaldship as to make a pun that is hard to interpret, provided one employ other distinctions than those which are indicated by the half-lines which precede. These cases are there, and many others, in which divers things have the same name in common.]"