Yeats' early poem The Song of Wandering Aengus is a poetic retelling of a famous Irish myth as I explored in this question. It's also a metaphor in which Aengus' quest for his fae lover is compared to the poet's quest for inspiration. However, I've always been fascinated by the final triplet:
And pluck till time and times are done,
The silver apples of the moon,
The golden apples of the sun.
On the face of it, this is a delightful evocation of the passing seasons. But it's also very specifically symbolic of alchemy, in a way that I can't find any reference to other than this take in a lecture from Langdon Hammer:
Yeats was trained in the occult disciplines of Theosophy and Gnosticism. Those traditions merge in his early work with European symbolism, and also with Irish cultural nationalism. Here, the gold and silver apples are specifically alchemical symbols of body and soul, and a kind of mystical image of earthly paradise.
He doesn't elaborate, telling his students not to worry about it. It made me curious to know what the specific symbolism of these fruits is?
Furthermore, the repetition of "time" and "times" strikes me as very specific and very odd. Since this is essentially the poem talking about mortality, why would it need to refer to "time", specifically - presumably Aengus' time - and "times" plural as though he's talking about time until the end of the world?
(Strictly speaking, these may be two separate questions but given that they're about the same three line lines and given that the answers might actually be linked, I thought I'd ask them together.)