A thought went up my mind to-day
"some way back"
Vague time markers throughout—"some way back," "could not fix the year." The thought itself is less important than the inability to pin it down.
"nor why it came"
Three "Nor" clauses in a row (where, why, what). She's cataloging everything she *doesn't* know about this thought.
"Have I the art"
Inverted syntax—normal order would be "I have the art." The inversion emphasizes her lack of skill to articulate the thought.
"came my way no more"
Final line is matter-of-fact, almost dismissive. The thought reminded her of something, then vanished—no drama, just gone.