Yoga is a generic name for any discipline by which one attempts to pass out of the limits of one's ordinary mental consciousness into a greater spiritual consciousness.
It was in 1590--winter. Austria was far away from the world, and asleep; it was still the Middle Ages in Austria, and promised to remain so forever. Some even set it away back centuries upon centuries and said that by the mental and spiritual clock it was still the Age of Belief in Austria. But they meant it as a compliment, not a slur, and it was so taken, and we were all proud of it. I remember it well, although I was only a boy; and I remember, too, the pleasure it gave me.
We must not forget that what I mean by the conquest of the world by spiritual thought is the sending out of the life-giving principles, not the hundreds of superstitions that we have been hugging to our breasts for centuries.
The art of sculpture is long ago perished to any real effect... it is the game of a rude and youthful people, and not the manly labour of a wise and spiritual nation.
You speak of doing good to the world. Is the world such a small thing? And who are you, pray, to do good to the world? First realise God, see Him by means of spiritual discipline. If He imparts power you can do good to others; otherwise not.