A Connecticut Yankee in King Arthurs Court by Mark Twain Chapter 43 Page 22

How empty is theory in presence of fact!

And this was just fact, and nothing else. It was the thing that would have happened, there was no getting around that. I tore up the paper and granted my mistimed sentimentalities a permanent rest.

Then, to business. I tested the electric signals from the gatling platform to the cave, and made sure that they were all right; I tested and retested those which commanded the fences — these were signals whereby I could break and renew the electric current in each fence independently of the others at will. I placed the brook-connection under the guard and authority of three of my best boys, who would alternate in two-hour watches all night and promptly obey my signal, if I should have occasion to give it — three revolver-shots in quick succession.