Why ‘ista’? LLPSI, XXXII, l.106.

Salvete.

The sentence at line 106 reads.

Nescio qui poeta ista scripserit.

I’m struggling to understand why the word ‘ista’ is used when I would, perhaps, expect ‘iste’?

I realise that the focus here is on the use of the subjunctive in indirect questions. I’d sailed past this line without questioning this, presumably simple matter of grammar. When I reread the passage I noticed that of course poeta whilst first declension is of course masculine. This explains ‘qui’ for me but I’m now at a loss as to what ‘ista’ is agreeing with?

Would anyone feel inclined to suggest quite what I’m missing? Many thanks in advance for any help.

ista = istās rēs

Thanks