Bhagavad Gita Verse 28, Chapter 2

avyaktaadeeni bhootani vyaktamadhyaani bhaarata |
avyaktanidhanaanyeva tatra kaa paridevanaa || 28 ||
 
All bodies are latent in the beginning, they manifest in the middle, O Bhaarata. In the end, they will become latent again, so why should you grieve about this.
 
avyakta : latent
aadeeni :  in the beginning, prior to birth
bhootani : all bodies
vyakta : manifest
madhyaani : in the middle
bhaarata : O Bhaarata
nidhanaani : after end
eva : only
tatra : this
kaa : why
paridevanaa : grieve
 
This is yet another important and profound shloka with layers and layers of meaning. Let's try to understand it to the best of our ability. Let us look at some examples.
 
The first example, which is an oft-quoted one, is the seed example. We know that we can hold the seed of a tree, say a mango tree, in the palm of our hand - it is that small. We also know that if we provide the seed with the right climate, soil, water and fertilizer, it will grow into a tall mango tree. The blueprint of the tall tree is present in that small little seed. In other words, the mango tree is latent until the seed is planted. In time, when the seed transforms into a sapling, and then into a tree, we can say that the tree has manifested out of the seed. And in the due course of time, the tree will eventually transform into wood or paper for human consumption, or get burnt and become one with the soil, or something else.
 
Today is the festival of Diwali when I'm writing this, so I have to add the example of the flowerpot firecracker. For those unfamiliar with it, the flowerpot firecracker is a fist-sized conical shape with a wick on top. After the wick is lit, the firecracker shoots up a dazzling fireworks display in the shape of a fountain, sometimes up to 100 feet tall. This display lasts for about 30-60 seconds. Here we can say that the fireworks display was latent in the firecracker, it came into existence when the wick was lit, and it ended when the gunpowder was exhausted and eventually absorbed in the air. To make it even more relevant, sometimes a hundred or so of these flowerpots are lit in succession, so that as one ends, another one begins.
 
Finally, here's a somewhat different example. I used to play Beatles songs in a band. We would rehearse most of the Beatles popular songs beforehand. When we began our performance in the club, we would ask the audience to request a song, which we would end up performing. Therefore, the song was latent in our memory, it would come into existence when we played it, and it would end soon thereafter, after having travelled into the listener's ears, and hopefully into their minds. Also, each time we played it, it would sound just a little different.
 
What's common in all the 3 examples? In each case there was a beginning where something was hidden or latent, then something happened that caused it to come into existence, and eventually there came a time when that thing no longer existed. In effect, the birth, existence and death of a tree is no different than the "birth", "existence" and "death" of the fireworks display or the song. Birth, existence and death are modifications rather than standalone events, therefore one should not grieve when someone or something comes to an end. It just transforms into something else.