Every motion is in a circle. If you can take up a stone, and project it into space, and then live long enough, that stone, if it meets with no obstruction, will come back exactly to your hand. A straight line, infinitely projected, must end in a circle. Therefore, this idea that the destiny of man is progressing ever forward and forward, and never stopping, is absurd. Although extraneous to the subject, I may remark that this idea explains the ethical theory that you must not hate, and must love. Because, just as in the case of electricity the modern theory is that the power leaves the dynamo and completes the circle back to the dynamo, so with hate and love; they must come back to the source. Therefore do not hate anybody, because that hatred which comes out from you, must, in the long run, come back to you. If you love, that love will come back to you, completing the circle. It is as certain as can be, that every bit of hatred that goes out of the heart of a man comes back to him in full force, nothing can stop it; similarly every impulse of love comes back to him.
- Swami Vivekananda
The Complete Works of Swami Vivekananda/Volume 1/Raja-Yoga/Patanjali's Yoga Aphorisms - Introduction