A Connecticut Yankee in King Arthurs Court by Mark Twain Chapter 18 Page 11

would I prize it? Of course not. And yet when you come to think, there is no real difference between a conscience and an anvil — I mean for comfort. I have noticed it a thousand times. And you could dissolve an anvil with acids, when you couldn’t stand it any longer; but there isn’t any way that you can work off a conscience — at least so it will stay worked off; not that I know of, anyway.

There was something I wanted to do before leaving, but it was a disagreeable matter, and I hated to go at it.

Well, it bothered me all the morning. I could have mentioned it to the old king, but what would be the use? — he was but an extinct volcano; he had been active in his time, but his fire was out, this good while, he was only a stately ash-pile now; gentle enough,