No discussion between two persons can be of any use, until each knows clearly what it is that the other asserts.

You have to run as fast as you can just to stay where you are. If you want to get anywhere, you'll have to run much faster.

One of the hardest things in the world is to convey a meaning accurately from one mind to another.

Without a plan, it doesn't matter which way you're going.

Who can tell whether the parallelogram, which in our ignorance we have defined and drawn, and the whole of whose properties we profess to know, may not be all the while panting for exterior angles, sympathetic with the interior, or sullenly repining at the fact that it cannot be inscribed in a circle?

Better say nothing at all. Language is worth a thousand pounds a word!

There are three hundred and sixty-four days when you might get un-birthday presents, and only one for birthday presents, you know.