So we materialists, we don't take into consideration that birth, death, disease and old age are the greatest miseries of our life due to our ignorance. But this ignorance has to be removed if one has to become out of these clutches of birth, death, old age and disease. This is not possible to remove by the so-called material science. Material science cannot remove these miseries. They can remove temporary, something artificially, some of our miseries. Just like we are feeling little warm. If the room was, had been air conditioned, we could feel some comfort. That is temporary. But our ultimate miseries are these four things: jara-marana-moksa. Jara means old age and birth, death.
Lecture on Bhagavad-gita 7.28-8.6, New York, October 23, 1966