Bacchylides' Ode 17 Dithyramb 3 centres on a ship-board argument between Theseus, son of Poseidon, and Minos, son of Zeus. Throughout the short poem, it is clear that both of the main actors claim their authority, power and sense of self from their divine fathers. The poem is, effectively, a dad-off. As such, the narrative depends entirely on the interplay between the sons and their fathers.
Minos, "heart pricked by lust" [line 8], lays hands on Eriboia (one of the Athenian maidens sent as tribute to Knossos), which causes Theseus to upbraid him for his actions. Although Theseus begins his reprimand with a clear acknowledgement of Minos’ patrilineal descent (“Son of mightiest Zeus…” [line20]), he soon begins to cast doubt upon the validity of Minos’ claim, in the form of a veiled question about who it was that Minos’ mother actually conceived by: "even if it is true" [line 29], Theseus says, that it was Zeus that your mother slept with, "still I too am son of a god" [lines 33-4]. In other words, you might not be, but I am (and as well as a dad-off, the poem is a Yo Mama).
Minos is understandably piqued, and calls on Zeus to uphold the family honour, at the same time returning the challenge, demanding that, if Poseidon is indeed his father, Theseus jump “with boldness into your father’s home” [line63], to retrieve a ring from the ocean.
Zeus listens, and his lightning bolt is the first clear indication in the narrative that there is any truth to any of these claims of divine parentage (although the contemporary audience would presumably have been familiar with the myths, whether or not they believed them or had gone “to the trouble of wishing to separate the wheat from the chaff” (Veyne, P. 1988 (trans. P. Wissing) Did the Greeks Believe In Their Myths? An Essay on the Constitutive Imagination. Chicago: University of Chicago Press).
Interesting here are the motives Bacchylides ascribes to Zeus for answering Minos’ prayer. Zeus, Bacchylides tells us, “engendering honor unsurpassed for Minos” [lines 68-9] sends the lightning “to make it visible to all” [line 70]: Zeus is proud of his boy, and wants everyone to know it.
Having demonstrated that he is indeed Zeus’ son, Minos repeats his challenge to Theseus: jump, and if you do it your father will grant you supreme glory throughout the well-wooded earth [lines 79-80]. There’s no question of 'if' here about Theseus’ parentage: Minos understands the trap Theseus now finds himself in, and how not denying that Poseidon is his father closes its jaws tighter. Regardless of the truth, Theseus has to jump: to remain on board would be a tacit admission of mortal parentage.
Theseus, of course, has no such doubts, and his “spirit did not give way” [lines 81-2]. Minos may have thought that Theseus was in a situation akin to the later medieval witch trials by water, and could only save his honour by drowning himself, but Theseus knows better.
That Minos (and, indeed, the other Athenians) was not expecting Theseus to jump is perhaps indicated by the amazement that fills his heart, and his attempts to hold the ship in its position [lines 86-9], but their fears are groundless because – of course – Theseus is indeed Poseidon’s son, and dolphins are already carrying him “to the home of his father” [lines 99-100].
There is an interesting contrast in the interactions between the fathers and sons; between Zeus and Minos and between Poseidon and Theseus. The former happens ‘on stage’, in front of the ship full of Athenian tributes and (presumably) crew. Minos asks Zeus to intercede on his behalf, and Zeus does. Minos asks Theseus to jump into the sea, and Theseus does. No-one asks Poseidon for anything, and the encounter between Theseus and his father happens in the depths of the ocean, ‘off stage’, unseen by any of the other characters in the poem.
In fact, in the literal sense it doesn’t happen at all, since although Theseus is taken to Poseidon’s halls, there is no indication that Poseidon is actually there, among the Nereids, in the company of Amphitrite.
Does this suggest that Zeus – although he loves his son – is only aware of him when called upon, whereas Poseidon is watching over Theseus whether called upon or not? And that Poseidon’s love for his son is so great that it is shared by his wife (not Theseus’s mortal mother), who gifts him a cloak and a wreath before he returns in splendour to Minos’ ship?