But what can you do with a singular story? Twain and all the witnesses are long dead, and no new observations can be made. All we have is his anecdote and whatever confirmatory recollections may have been recorded by the others in his story.
It is, in principle, reproducible and testable. Ask every husband, wife, sibling, parent to a soldier involved in an ongoing conflict (such as Russia/Ukraine war, Israel/Palestine war) to record those “sentiments of dread for a loved one”. See if it matches with recorded casualties.
I think you’re trying to point towards multimodal distributions ?
If you can decompose P(X) as P(X) = P(X|H1)P(H1) + … + P(X|Hn)P(Hn), and the P(X|Hn) are nice unimodal distributions (like a normal distribution), you end up with a multimodal distribution.