|The jewel in the lotus is a wonderful metaphor for the essential nature of mind. It integrates two very different approaches, recognizing that there is a worthy role for striving, for engaging in methods, for growth and development; and at the same time recognizing that all these methods are fundamentally designed simply to bring to light what is already there, in all of its perfection, in all of its completeness. This is the pure fountain of loving-kindness and wisdom we are trying to cultivate.
The mantra OṂ MAṆI PADME HŪṂ is associated with Avalokiteśvara, the embodiment of enlightened compassion, and the mantra is the verbal articulation of that same quality of compassion. Among the many interpretations of the mantra, here is one I find especially meaningful. Oṃ signifies the manifest body, speech, and mind. Maṇi in Sanskrit means “jewel.” Padme, pronounced pémé in Tibetan, means “in the lotus.” Hūṃ, pronounced by the Tibetans as hoong, is a syllable suggestive of the deepest, essential, transcendent nature of consciousness. So the mantra starts out from the manifest state of the body, speech, and mind, then through the metaphor of the jewel in the lotus, goes to the depths of consciousness.
From The Four Immeasurables: Practices to Open the Heart by B. Alan Wallace, pages 23–24