"Actually, there is something of grave importance I need to discuss with you."

"I understand ye wanted to see me on a matter of grave importance."

"What you have seen is indeed of grave importance," he said aloud.

You said that it was a matter of grave importance to every person alive.

We will give consideration to what you have said because it is of the gravest importance.

I am most interested to hear what you consider to be of such grave importance.

"I have come to discuss a matter of grave importance with you."

It was obvious he had something of grave importance on his mind.

We burst out laughing, at a moment of grave importance to us both.

"This is an issue of grave importance to us and we are asking him to listen."