Word Meanings
Translations
The Supreme Lord said: While speaking learned words, you are mourning for what is not worthy of grief. Those who are wise lament neither for the living nor for the dead.
Krishna begins his teaching by pointing out Arjuna's intellectual hypocrisy: he talks like a sage but grieves like a fool. The truly wise understand the eternal nature of life and do not grieve for temporary forms.
You're trying to sound smart, but you're crying over things that don't matter in the long run. If you really understood how life works, you'd know that nothing truly dies, so there's no reason to be paralyzed by grief.
Multi-Layer Explanation
This is the start of the 'Sankhya Yoga'—the analytical path to understanding the distinction between the eternal Soul (Atman) and the temporary Body.
Shankaracharya emphasizes that grief is born of ignorance (Avidya) and can only be removed by Knowledge (Jnana).
Arjuna has just surrendered to Krishna, and these are Krishna's first words of instruction.
Life Application
Check your 'learned words' against your emotional reactions. Are you practicing what you know to be true?