I came across this passage in Heart Essence of the Vast Expanse by Anne Klein:
"All the foundational practices move energy through the body; this is one element of their profundity.
Tibetans attribute the power of their practices, transmissions, and lamas to a type of energy known as "waves of splendor" (pronounced jin lab, rhymes with pin drop"). The first syllable, jin, means "that which has been given or bestowed," as in bestowed by the king." Jin also means "grace", or "gift", and , in some contexts, "splendor". The second syllable, lab, means "wave", like the waves of the ocean. Early Tibetan kings were considered to be direct descendants of the gods, and so these kings were imbued with supernatural qualities such as jin - - pomp, splendor, and magnificence.
Transmission is understood to occur through subtle flows of splendor carrying all the knowledge and energetic patterning held by one awakened person to another in the process of awakening. Thus, the jin lab that began as the splendor of kings later became, in Buddhist understanding, the waves of grace, or surges of splendor that are the most profound gifts of the lamas. This is what comes through the mind body in practice. This is what is transmitted from teacher to student through teachings and, most explicitly, through initiations. The teacher's presence allows a full transmission of the blessings embedded in their being to be communicated. Still the ultimate source of blessings is reality itself, chonyi. In this way, blessings are reality releasing its intrinsic energy to practitioners,until they recognize the source for what it is.
Put another way, practice allows one to recognize experientially that transmission emanates from the same reality to which it points." - - -pg 9