Human mentality is like duckweed; our true nature like the water beneath. This true nature goes by many names: spirit, Holy Spirit within, primordial mind, Big mind; each different flavours of the same true Being. It is the essence we are born with and do not lose when we die.
Human mentality has fewer names as everyone has it; it is the "I" that develops as we grow. It is the psyche, the soul: our thoughts, feelings, opinions, values. It includes everything social like our status and good name. Human mentality is everything we share from our culture, including language.
Why "duckweed"? Simply by being there each plant spawns others around it. In the same way thoughts spawn others simply by being in our minds. It is possible to be mindful (mindless but with a full awareness of being) but it usually doesn't last long.
As soon as one thought appears others quickly follow until it seems we live in a world of ideas and mistake them for reality. For example, how many people do you know think money is real? And how many are immune to it, knowing it is simply a shared idea that enables fair exchange?
Where ponds are people, most of the ponds in the world are covered with duckweed. Some even go so far as denying the existence of the water that sustains it, claiming duckweed is all their is. This is not surprising as we are all infected. Our parents live in the duckweed world, so that is the world we ourselves learn, too.
Distinguishing between the duckweed and the water is simple: if you can express it adequately in any cultural medium (art, dance, music) but most commonly in words, it is "duckweed". If it defies description it is either fantastic rubbish or "water", the true ground of being.
To survive death we must have some impact on the "water", not simply float on top of it. At this point the analogy fails, but perhaps I can use an illustration from Jesus' teaching. He said (Matthew 6) that those who prayed in public received their reward in full but those who prayed with no earthly recognition or response are heard.
It is as if the "duckweed" world is internally consistent, balanced. Action and reaction match. Human mentality expects justice in these terms. Jesus told another story (Matthew 20) about a man hiring labourers for his vineyard. Those who had laboured all day under the hot sun were paid the same amount as those who turned up for the last hour. Reading this, we feel their aggravation.
A Rend in the Universe
Yet the point is, sometimes things don't balance and they are not supposed to. There is more to life than the human mentality duckweed. Jesus told us (Matthew 5) even the heathen love their friends; we are to love our enemies (despite knowing they won't love us in return).
This is as if a rend is torn in the social universe, allowing God's grace (or whatever) to pour in. Such a tear creates enormous pressure to close it again. For example, loving your enemy usually means loving the enemy of your friend, too. But your friend, who simply sees you "giving support to the other side", will not take kindly to such treacherous betrayal.
However, in the meantime, something else has happened. While your enemy was loved from a completely unexpected source, this rend in the universe moved the water beneath your duckweed. Once again the analogy fails. Think of well-worn slippers, the imprint of your bottom in an armchair or how two people in a good relationship 'fit' each other.
When these effects occur within the human world, the circle is closed; balance is restored with no residual effects. But when they break through beyond the cultural sphere, they still leave an impression, but beyond the cultural sphere. As that action is repeated, so the impression becomes more lasting.
So loving our enemies creates only trouble here (morality abhors injustice). However our action has also made an impression in the spiritual world, beyond.
We are born with undeveloped spirits. Most people live their lives entirely within the balance of social norms. When they die, their spirit (the water underneath the duckweed) is still undeveloped. Their lives have made no ripples there, no impact upon that which outlasts death. So everything they are dies when their bodies are unable to continue ensuring they are able to continue.
But to the extent we have broken through this world and made an impression in the lasting "stuff", that part of ourselves has become eternal. The primordial essence we were born with has been changed. It is this change that will always be. As an action of a unique being, no matter how poorly formed, that unique being is now a part of something that will continue beyond their body's life.
The idea of a wax seal makes sense to me. Somehow, when we make a mark in the world of Spirit, our unique "seal" is imprinted in the "stuff" of God. God is life, our life, the water that feeds our duckweed. Of course our "seal" will look different, and some of us will have more "complete" imprints than others, but this imprint is even more alive than our duckweed was, being part of God Himself: the eternal, living "water".
(the sages of Huai nan, c.300 B.C.E.)