In fact, you would have to be identical to the original subject.

How, and why, had he been led so far from the original subject?

She made a face when he laughed, and went back to the original subject.

You look at it, and you see nothing like the original subject.

Shall we get back to our original subject of discussion?

Now let's forget all this and get back to the original subject.

Being at a loss for comment, I returned to the original subject.

That pleased him enough to return to the original subject.

The original subject might share the experience (primary social sharing) with 5 other people.

But that brings me back to the original subject of my simple wonder.