Concentration signifies the state of being at a centre (con and _centrum_). Applied to thought, it is the act of bringing the mind to a single point. Each human being must practise concentration subjectively and objectively. In other words, each human being aims with more or less precision at concentration on a point within and a point without his own world. Concentration "without" is illustrated when you devote all your attention upon Nature, such as learning a trade, a profession, a science, an art or some form of business. This is _Evolution_, outgoing or positive mental energy. I shall call this Objective Concentration. Concentration "within" implies.
