From Rigpa Wiki
The path luminosity (Tib. ལམ་གྱི་འོད་གསལ་, Wyl. lam gyi 'od gsal), also called the child luminosity, is the nature of our mind, which, if introduced by the master, and if recognized by us, we can then gradually stabilize through meditation, and more and more completely integrate into our action in life. When the recognition and integration is complete, realization occurs. Child luminosity is like a key the master gives us to help us open the door to the recognition of the ground luminosity, as, even though the ground luminosity is our inherent nature and the nature of everything, we do not recognize it, and it remains as if hidden.