I like the metaphor of the mind being like a garden.
In the beginning, gardening involves effort. One has to choose the seeds carefully, prepare the soil, ensure the conditions are right for those seeds. Plant them, water them, nuture the seedlings that sprout, protect them from predators, and keep the young plants safe until they are big and strong enough to take care of themselves. These are the seeds of non-greed, non-hate, non-delusion.
At the same time there are many dormant seeds in the soil from a previous garden, a previous existence. And when these sprout, these are the weeds that have to be removed from the garden; because if nothing is done about them, they will eventually take over, become difficult to manage, and create a canopy of leaves that shade the garden and starve the plants you are trying to cultivate of light, water and nutriment. These weeds are greed, hatred, and delusion. And they sprout from the seeds of longing, aversion, and ignorance.
In the beginning one has to put in the right causes and conditions for the garden to grow and flourish. This involves a sense of self, the ego. The ego is the gardener, and one uses that sense of self, that craving for becoming to do the gardening project.
If the work is not fully done in time for the ending of the seasons and the death of winter. Whatever seeds are in the soil at the end, will sprout to become the next garden, our new life in the Spring.
If we have cultivated non-greed, non-hate, non-delusion, even if a few seeds of greed, hate, and delusion remain and manage to sprout in the next garden. The weeding will be easier and less onerous than before; and the seeds of non-greed, non-hate, non-delusion will be present in the soil in larger quantities, and they will also sprout to greet us on the other side, and be hardier and easier to cultivate, much stronger and better at defending themselves and holding their own.
It can be a gradual process that may take many seasons. But eventually there will come a point when enough effort has been made. The garden has flowered and born fruit. and from that point the garden will be able to take care of itself; then the gardener will no longer be needed and the ego can step aside. Greed, hate, and delusion will never take root in the mind again. And what is left is peace and the end of suffering. Nibanna.
I quite like looking at it like that (-: