Train of thought

The train of thought, stream of thought, chain of thought refers to the inteconnection in the sequence of ideas expressed during a connected discourse or thought, as well as to the sequence itself, especially in discussion how this sequence leads from one idea to another.

When a reader or listener "loses the train of thought", i.e., loses the relation between the consecutive sentences or phrases, they lose in the comprehension of the expressed thought.

Inability to maintain one's train of thought is anong the sympthoms of thought disorder, either because of mental illness or drug abuse.

The term "train of thoughts" was introduced and elaborated as early as in 1651 by Thomas Hobbes in his Leviathan in a somewhat different meaning: By Consequence, or train of thoughts, I understand that succession of one thought to another which is called, to distinguish it from discourse in words, mental discourse. When a man thinketh on anything whatsoever, his next thought after is not altogether so casual as it seems to be. Not every thought to every thought succeeds indifferently.