It means that a person is born with a ‘ready record’ containing certain information on the past he/she did not attend him(her)self, but where his/her great-grandmas, great-granddads and millions of unknown people were present.
And there are no mysteries or esotery in it as somehow scientists proved the fact and let all the others admit it. Thus, it is clear with the unknown known past: while a person learns the past of his ancestors by genetic memory, the collective unconscious lies in ethereal sphere.
Today we can use two terms introduced and used by philosophers, physicists, theosophists and mystics. These are Akashi Records and earth energoinfromational field.
Both of them name the space filled with the energy of the fifth primary element aethyr. While the first four are present in the physical world and they are transformed in each other and change gradually, the fifth one being a quintessence of the first four is an eternal aethyr which never disappears as it is out of time and space boundaries. Today’s interpretation uses the term ethereal Space sphere.