‘The Workhouse’ – Tolkien’s Purgatory

[Kuruharan]

I don’t understand why Grace takes effect only after a long period of punishment, as grace waives punishment in my understanding of Christian doctrine, but apparently he saw it that way.

It is perhaps a mistake to view this as punishment. It could be corrective and I would not equate correction with punishment. Something like Niggle being in the shop for repairs. Grace was what allowed him to proceed on to the Workhouse, even though he had not brought any of the required luggage. However, receiving Grace did not make Niggle entirely ready for what was to come. Niggle was not ready for Paradise because he perhaps could not understand it and not fully appreciate it. He had to go through the Workhouse to have a final reshaping of his mind. It is interesting to note that, if anything, Niggle developed a more practical outlook during his stay.

What about the necessity for repentance? Surely repentance requires that the individual be purified

Not necessarily. Repentance is more of the realization of the need rather than requiring a purification process to get to it.

If the individual is not so 'purified' by experience, how would they realise they needed grace?

If Niggle had been purified already he would not need the Grace. Purification sort of eliminates the need for repentance.