Metamorphoses Book V, the story of Proserpina. At this point Proserpina's mother Ceres is still looking for her daughter.
Sicaniam repetit, dumque omnia lustrat eundo,
venit et ad Cyanen. ...
"while everything she wanders over... by going (?)"
Loeb offers this "she came back to Sicily, and in the course of her wanderings here she came to Cyane".
The thing is, I'm trying to understand why eundo would be in that particular case, dat./abl. m./n. s. (and indeed which of these cases?).
I'm puzzled not least because here we learn that a gerundive is passive (and also the future passive participle).
But in the first place, eo, ire is not transitive. So how can you have a passive participle at all?
As for any suggestion in this context that it might have some future meaning, I don't get that at all.
I'm quite happy to just accept that eundo is maybe abl. n. s. and means "by going", if I must, but I feel that I'm somehow missing some meaning: why (apart from metrical requirements) did Ovidius add this word: what does it add and mean?
And why this case, gender and number, whatever the former are?