Bhagavad Gita comes from the epic Mahabharata written by Ved Vyasa thousands of years ago. Lord Sri Krishna is a universal teacher and Bhagavad Gita is a gift for mankind to save them from sorrow.
You can learn more about Introduction to Bhagavadgita at Hindu American University. But you must know "how to study Bhagavad Gita book”.
Always think of one thing. You came into this world alone and wept. Among them, you will find many objects that do not belong to you. There's no use crying over these things. Always try to be happy with yourself.
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You are the only real person in the universe. Everything else is your manifestation. Age does not cause death. This is an indirect consequence of the continuous destruction of our bodies by the six enemies living within us. When we drive these enemies out of our bodies, we become immortal.
Your wealth, your husband, your children, your relatives and friends will not follow you, but the Dharma. Dharma is your true friends, followers and relatives.
Take happiness, the ultimate happiness, inside you, not outside, because only you are real and everything else is an illusion.
From birth to death we lose our entire lives searching for happiness that is elusive in other places, while we ignore its fullness within us.
If you know everything about yourself, you don't need to know anything in the universe.