The most profound of which
is the fact we have lived many lives
and learned many things during those lives

Lesson one is simple, We are all One family
I mean that very literally :)

If you go back far enough there had to be a first man and first woman, no matter what creation/evolution
story you ascribe to.. it comes down to basic fact.. we are all descended from the same basic family tree.
The only reason for racial differences was due to climate and diet in different places in the world.
Read any good book on the origin
of mankind and you will see this to be fact

Therefore

We are all one Race ... Human

Lesson two
We are no different than the very Stars themselves

As the old Philosophers said.. there is no such thing
as empty space ,its an illusion .. " May the force be with you " as the current Movie Genre says,
and it happens in this case , to be right .The Primordial force
that is all things .. is also .. US

Lesson three
We Know without being told , we have all done this one :)

The times when we need to figure out something
and suddenly just know what to do

No one told us , we didn't read it anywhere , and we have clue one on how we came up with it,
there is no logical progression that would give us the new thought
Its just there ! This is knowledge of the past
forcing its way to the present, as we have been here before ,
and have reincarnated into another form

There are many many more, but I think you get the idea :)

Ok why do we do this ?

Why come back .. isn't once enough ?

You can answer that for yourself ,does anyone live long enough
to learn all they want or need to know ?

No

This is the way of it in the modern world

The first 20 years are spent getting out of childhood,
the next establishing ourselves in work, family community , the next 20 is maintaining that ,
and preparing for the 20 after that . Now we are thinking about , but not ready for retirement,
then we do retire. Now we are 60 something, during all this we manage to live and learn and grow ,
but lets face it we spend a great deal of our lives just maintaining our lives,
and it was no better for our ancestors who had even less time or leisure than we

But they did have a much greater connectiveness than we,
and we need to regain what has been lost

So is once enough to become an enlightened soul ?
To really understand our place in the Divine
scheme of things ?

I would say not, so we return , learning and growing , until hopefully
we learn enough for all mankind
to mature as a race, to where we become one People

This is the balance for our relatively short lives ,
this ability to journey however often we must .. until we understand .. some do
.. Like Quan Yin .. our Lady of Compassion, and she lives in the dragon realm
between the worlds to aid other souls in reaching this understanding

Or Buddha .. the Enlightened One so named as he shared
his understanding with his fellows before he passed
from his last life

There have been many others to show us the way
We can follow in their footsteps

May your tread be sure and strong on the way :)