Spiritual power, if it is to grow and mature, needs a period in the darkness of a sealed vessel. Within this vessel it grows until it bursts its covering and is “born” into the world. Certain vessels are imbued with the necessary power of containing and nurturing a supernatural principle. The quality is known as utsubo or “hollowness” to the divine… So is the cave or darkened room in which the religious ascetic secludes himself.
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