The less a tourist knows, the fewer mistakes he need make, for he will not expect himself to explain ignorance.

The President may indeed in one respect resemble the commander of an army in peace, but in another and more essential sense he resembles the commander of a ship at sea. He must have a helm to grasp, a course to steer, a port to seek. He must sooner or later be convinced that a perpetual calm is as little to his purpose as a perpetual hurricane, and that without headway the ship can arrive nowhere.

Nature, to be commanded, must be obeyed. The imagination must be given not wings but weights.

My own conclusion is that history is simply social development along the lines of weakest resistance, and that in most cases the line of weakest resistance is found as unconsciously by society as by water.

One sought not absolute truth. One sought only a spool on which to wind the thread of history without breaking it.

Laplace would have found it child's-play to fix a ratio of progression in mathematical science between Descartes, Leibnitz, Newton and himself

Friends are born, not made.