The Doctrine and Practice of Yoga

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 the withdrawing of attention from the external world and the placing of mind on "God," "Spirit," "Heaven," "Religion," "Peace," "Nirvana," "Eternity," etc. This is Involution, i.e., incoming or negative energy.

When Objective Concentration alone is practised, you develop into a hard-headed, practical man of the world or a successful man of business.