In the sixteenth book of the Iliad, Zeus watches his own son Sarpedon fight beneath the walls of Troy and face death at the hands of Patroclus. Homer has the king of the gods openly consider saving him, asking aloud whether to snatch Sarpedon from the battle and set him down alive in his own rich land of Lycia. Hera's answer, that every other god with a mortal child fighting at Troy would resent such an intervention, and that fate has already marked the day of Sarpedon's death, settles the matter. Zeus does not overrule what has been allotted. He mourns instead, sending down a rain of blood in grief, and lets his son die on schedule.
The scene recurs in miniature during the climactic duel of Hector and Achilles in Book Twenty-Two, where Zeus sets the two heroes' portions on a golden scale and watches Hector's sink toward death, at which point even Apollo, Hector's divine protector, withdraws. The image of golden scales implies a mechanism external to the gods' own preference, one they read and obey rather than operate. Later Greek writers took both episodes as proof that Homeric theology placed a limit on divine will that the Olympians themselves treated as binding, however painful, an idea some ancient critics found troubling enough that they proposed allegorical readings to soften it, and that Plato singled out for censure in the Republic precisely because ordinary listeners took the gods' grief as sincere and their restraint as real.