a train of thought

train of thought

One's uninterrupted progression of thinking. When the phone rang, it derailed my train of thought—I totally forget what I was talking about! Please don't interrupt my train of thought when I'm writing.
See also: of, thought, train

a train of ˈthought

the connected series of thoughts that are in your head at a particular time: The phone ringing interrupted my train of thought.
See also: of, thought, train
References in classic literature ?
So when I saw you throw down your paper and enter upon a train of thought, I was very happy to have the opportunity of reading it off, and eventually of breaking into it, as a proof that I had been in rapport with you.
Then your eyes fixed themselves upon your newly-framed picture of General Gordon, and I saw by the alteration in your face that a train of thought had been started.