Bhagavad Gita Chapter 02, Text 28

Bg 2.28

avyaktadini bhutani
vyakta-madhyani bharata
avyakta-nidhanany eva
tatra ka paridevana

Word for word: 
avyakta-adini — in the beginning unmanifested; bhutani — all that are created; vyakta — manifested; madhyani — in the middle; bharata — O descendant of Bharata; avyakta — nonmanifested; nidhanani — when vanquished; eva — it is all like that; tatra — therefore; ka — what; paridevana — lamentation.

Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
All created beings are unmanifest in their beginning, manifest in their interim state, and unmanifest again when annihilated. So what need is there for lamentation?

Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Accepting that there are two classes of philosophers, one believing in the existence of the soul and the other not believing in the existence of the soul, there is no cause for lamentation in either case. Nonbelievers in the existence of the soul are called atheists by followers of Vedic wisdom. Yet even if, for argument’s sake, we accept this atheistic theory, there is still no cause for lamentation. Apart from the separate existence of the soul, the material elements remain unmanifested before creation. From this subtle state of nonmanifestation comes manifestation, just as from ether, air is generated; from air, fire is generated; from fire, water is generated; and from water, earth becomes manifested. From the earth, many varieties of manifestations take place. Take, for example, a big skyscraper manifested from the earth. When it is dismantled, the manifestation becomes again unmanifested and remains as atoms in the ultimate stage. The law of conservation of energy remains, but in course of time things are manifested and unmanifested – that is the difference. Then what cause is there for lamentation either in the stage of manifestation or in unmanifestation? Somehow or other, even in the unmanifested stage, things are not lost. Both at the beginning and at the end, all elements remain unmanifested, and only in the middle are they manifested, and this does not make any real material difference.

And if we accept the Vedic conclusion as stated in the Bhagavad-gita that these material bodies are perishable in due course of time (antavanta ime dehah) but that the soul is eternal (nityasyoktah saririnah), then we must remember always that the body is like a dress; therefore why lament the changing of a dress? The material body has no factual existence in relation to the eternal soul. It is something like a dream. In a dream we may think of flying in the sky, or sitting on a chariot as a king, but when we wake up we can see that we are neither in the sky nor seated on the chariot. The Vedic wisdom encourages self-realization on the basis of the nonexistence of the material body. Therefore, in either case, whether one believes in the existence of the soul or one does not believe in the existence of the soul, there is no cause for lamentation for loss of the body.