अव्यक्तादीनि भूतानि व्यक्तमध्यानि भारत। अव्यक्तनिधनान्येव तत्र का परिदेवना ॥

avyaktādīni bhūtāni vyakta-madhyāni bhārata avyakta-nidhanānyeva tatra kā paridevanā

Beings are unmanifest in their origin, manifest in their midmost state, O Bhârata, unmanifest likewise are they in dissolution. What room then for lamentation?

In plain words: Beings are unseen before birth, seen during their life, and unseen again after death. So there is no reason to weep.