The Train of Thought

I find myself sitting here with a book,
For what into my head once just popped,
For word and for phrase, I page , and I look,
And wonder why has the train stopped.

Oh, train of thought, upon your apt track,
Move on, ever forward the pen.
Bring facile words and fit phrases back;
Rumble on through my mind once again.

It's the silly fear and dread, numbing thought,
That impersonates will to refuse,
To prod with the should and the must and the ought,
Drive away the ingenious muse.