Things of the world never last. All things come and go. People come and go, horses come and go, even the mountains will eventually go.
Live life not in the physical world, but rather, in the spiritual world as it's the only one that last forever.
That said, as man is made from the dust of the ground, there is forever a bond with the physical world, one that's only broke at the end of life, yet the spirit lives on.
Still haven't figured out the 3 greatest things in the world have you?
Sorry to see Luna go, I know how much you enjoyed her.
For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.