question regarding comma
 

Hi. I am wondering why there is a comma in one of the sentences below. Both of the sentences came up in the same grammar lesson. However, one of them has a comma, and the other doesn't. If anyone can answer this question, it will be the most appreciation. Thanks.

He left the country, never to return.
I awoke to find the house on fire.

Re: question regarding comma
 

In the first sentence, the non-finite clause is additional information - a sort of afterthought. the comma reflects the dramatic pause that would probably occur in speech between the two thought groups.

In the second sentence the non-finite clause is an integral part of what the speaker wants to say. There is a single thought group, and there would be no pause. And so there's no comma.