
On the same vein as tracks. When you forget what you are saying you can say "I lost my train of thought." Your "train of thought" is the flow of ideas that you are currently having.
Oh I see! It reminds me of “lose track of time” Are they in the same vein?
They are similar! However, this track that you mentioned is not the train tracks, but rather keeping track(monitoring) of something. Even so they still are from similar ideas though so good catch.
I got it! That track feels more like path or flow, not a track for train of thought. These kinds of expressions are so fun!