In this preface to Rāja-Yoga by Swami Vivekananda, the author frames Yoga as a rigorous science rather than a collection of miracles. He critiques both "surface scientists" who dismiss mental phenomena without investigation and the superstitious who attribute such events to supernatural beings.

Vivekananda argues that "miracles" are actually natural effects of subtle laws. He asserts that humans are conduits for an infinite ocean of internal power; thus, fulfilled prayers come from within the self, not from external deities. Relying on "beings above the clouds" leads to spiritual decay and weakness. By practicing Rāja-Yoga, one gains perception of the subtle causes behind gross effects, ultimately leading to the liberation of the soul through perfection and self-reliance.