The Theory of Groups is a branch of mathematics in which one does something to something and then compares the result with the result obtained from doing the same thing to something else, or something else to the same thing. ↗
When I fly in a helicopter, I insist there be two sets of controls, one for me in case something happens to the pilot. I'm no expert, but I know enough to at least get the thing on the ground. Nothing scares me like the thought of not being in control. ↗
The death of Mrs. Lincoln was a serious loss to her husband and children. Abraham's sister Sarah was only eleven years old, and the tasks and cares of the little household were altogether too heavy for her years and experience. ↗