Rather than deja vu, which is the mistaken belief that something is happening again, does yishda involve something actually repeating itself?
Yes, it involves something actually repeating itself, though this is not the main reason why it's different from "typical" deja vu. If so, an external event?
No One's reaction to an external event?
No A train of thought?
One could call it a "train of thought", and this would certainly be a much better description than "external event", though not the way one would ordinarily refer to it.Or is it like deja vu in that it is a mistaken belief?
There is a mistaken belief involved too. Does it have anything to do with premonition of the future? Remembering something "through new eyes" once you are older?
No to rest.Could yishda be phrased as: a type of memory that ____?
Only very awkwardly.A memory is involved, but it's unlikely someone who knows what a yishda is would call it a "type of memory".Does yishda always involve remembering a specific type of thing?
Yes if so, a person? an emotion? an event?
This is the only one that works, although some may not call it an "event".If it's a weird thing one's brain does, I bet I have also experienced it at some point.
We'll see...