In energetic terms when the soul incarnates into body it remains attached to 'source' by a silver thread. This is the life-line in a sense. It is through this that our intuition and 'memories' of past lives as well as access to Akashic records and libraries of collective knowledge can be activated. Jung believed in a collective consciousness and supra-consciousness, realms from whence other forms of 'knowing' can be 'downloaded'. Many psychics use this energetic field to gain insight into imprints of past and future events.
The silver thread itself however is also very personal. Each of us has one. Coming into the physical dimension is in a sense a bungy jump from the higher dimensions to this lower vibration which sustains form and substance. This is the greatest leap of faith any of us shall ever make. During episodes of astral travelling, unconscious travel in a dreamstate or out of body experiences, it is the silver thread which maintains the link to the physical. Whilst it is in place you will always return. At the end of our lives however, it wears very thin and eventually dissolves. This has been observed by many people visiting the dying. It is the cord which binds us both to mortality and to eternal life guiding us back home.