"The windows of the mind all have their latches on the inside. They cannot be pried open from without by sense stimulation. Loud music and other excitants only push the windows more tightly shut. The use of hallucinogenic drugs, to the extent that they do work from within, is tantamount (as yogis say) to breaking one’s mental windows outward with a sledgehammer. (In this sense, the drugs are, quite literally, "mind blowers.") What if one cannot close his mental windows to harmful influences, or determine how widely the windows are opened when he does open them? Once they have been broken, he is at the mercy of every shift in the weather. No longer the master of his own fate, the habitual drug user, though sometimes delighted by clement breezes of inspiration, becomes a prey to every other sort of wind as well. In time he finds his mental home devastated by the storms that also form a part of the universal influences, storms against which he finds himself wholly unprotected. He becomes ineffectual both egoically and spiritually—unable to impress himself and his ideas on others, and equally unable to relate to the universe on a higher than personal level.
Man cannot be satisfied for long without spiritual awraeness. The need to expand his consciousness is at least as basic as his physical needs, even if it is too sensitive to shout its demands. Every time one reads a book or asks a question, he expresses this spiritual urge. Expansion of consciousness, rightly accomplished, is both our duty and our divine destiny. But it is important that the growth be natural, not prodded and stretched with chemicals or ego drives. That the science of yoga works with nature, not against it, may be seen in the increased ability of the yogi to relate meaningfully to the natural order around him. He becomes more sensitive to the needs of others, not less so. Neither rejecting the world, nor yet embracing it possessively, he learns that sort of unselfconscious give-and-take which is perhaps the surest sign of a well-integrated human being.
Yoga practice heightens one’s awareness of external influences. Thus it makes one more aware of the need for surrounding oneself as much as possible with uplifting influences. The effort to practice yoga entirely on one’s own, while yet surrounded daily by worldly influences that, of their very nature, dilute one’s dedication, has caused many a beginner eventually to give up despite inner improvements that are as obvious to everyone else as to himself. Satsanga (spiritual company) is stressed again and again for great yogis as one of the basic ingredients for spiritual success.”
This comes from the back cover of a vinyl recording of yoga instruction that I found. It’s called “Make Me the Sea, yoga postures for self-awareness”, led by Swami Kriyananda, a small bearded Romanian man.