How to understand the phrase "Διὸς μεγάλου διὰ βουλάς" from Hesiod's Theogony?

Question

πεύθετο γὰρ Γαίης τε καὶ Οὐρανοῦ
ἀστερόεντος οὕνεκά οἱ πέπρωτο ἑῷ ὑπὸ παιδὶ δαμῆναι,
καὶ κρατερῷ περ ἐόντι, Διὸς μεγάλου διὰ βουλάς
--- Theogony 463~465

For he had heard from Earth and starry Sky that, mighty though he was, he was destined to be overpowered by a child of his, through the plans of great Zeus. (Loeb Classical Library)

For he learned from Gaia and starry Ouranos
that it was fate that his own son would overthrow him,
although he was powerful, by the plans of great Zeus. (Richard S. Caldwell)

Both translations read to me like a prophecy that Kronos was destined to be overpowered by Zeus through his future plans. But people claim it means that Zeus willed Kronos' destiny before he was even born.

During my research I found at least some Greek authors (Stauros & Blachos) who seemed (I don't know much Greek) to agree(?):

απ' την βουλη του μεγαλου Δια*
from the will/plan of the great Zeus*

*Σαν υα προυπηρχε η βουλη του Δια απο την γεννηση του. Η βουλη του Δια ταυτιζεται εδω, με την Μοιρα, στοιχειο αχρονο.
*As if the will of Zeus had existed since his birth ...

---

More different translations:

despite his strength, as the will of great Zeus decreed. (Norman O. Brown)

no matter how mighty Cronus was,
deliberate action by a great god would win out. (C.S. Morrissey)

powerful though he was, through the designs of great Zeus. (M.L. West)

That his own child would conquer him, powerful though he was, And this was bound to happen through the plan of mighty Zeus. (Catherine Schlegel & Henry Weinfield)

that it had been ordained for him,
for all his great strength,
to be beaten by his son,
and through the designs of great Zeus. (Richmond Lattimore)

Answer 1

I don't think there's a real reason to think that Zeus "willed this before he was born." The word βουλή doesn't indicate any pre-existing connotations. It's not that Zeus has pre-ordained the overthrowing of his father, but rather that fate has pre-ordained Zeus to accomplish it.

While βουλή can mean "grand design", it doesn't have to, and can indicate just ordinary plans or even just effort:

will, determination, esp. of the gods, Il.1.5, etc.
generally, counsel, advice, opp. μάχεσθαι, Il.1.258, cf. 2.202, etc.; “κακὴ β.” Hes.Op.266

It's true that the line can be misunderstood, and it was already in antiquity. However, the ancients still didn't think the plan was Zeus', just that Zeus was foretold by Gaia and Uranus before he was born. In other words, it can be read, "You will be defeated by a child, and his name will be Zeus." It cannot however be read, "You will be defeated by a child, and Zeus ordained this."

The text's lack of clarity here is probably, as TKR notes, due to its formulaic nature. It nicely fills out the line, but as Martin West (1966) already pointed out, "[it] is from Hesiod's view-point that the overthrow occurred "Διὸς μεγάλου διὰ βουλάς", i.e. "Kronos was not told 'Zeus has a mind to overthrow you'", just that his son (παιδὶ) would. We know from Hesiod that Zeus led the overthrow, so he has to be the child in question. Hesiod actually clarifies and expounds on this point at 492:

νικηθεὶς τέχνῃσι βίηφί τε παιδὸς ἑοῖο. vanquished by the skills and strength of his son

The βουλή must refer to the plan, and τέχνῃσι βίηφί τε are the means by which he accomplishes it. Note that nowhere else in the Theogony does it indicate that Zeus had pre-ordained it, nor is there even a hint of it.