When I first heard the expression, "pain is inevitable,suffering is optional", I did not understand its meaning. I was not aware of any difference between pain and suffering. Years of mental suffering have finally made me aware of that difference.
Pain is part of the unavoidable set of experiences of living organisms. It is the pain of having a body that can be hurt, feel hunger, be thirsty, get sick, and die. All organisms with even a rudimentary nervous system can feel pain. But only humans can suffer. Suffering is when we resist the reality, the presence, of pain. We resist when we say that this experience should not be happening. Life unfolding will contain pain; when we resist it, fight it, get angry or upset about what is happening, then we add the layer of suffering on top of the pain. I now understand that pain is an inherent part of life and that it is the my act of resisting what is happening that adds the much more intense suffering to my life.
For example, I can become ill or have my belongings destroyed by an act of nature and that will be painful. I add suffering to it by asking questions such as, "What did I do to deserve this?";"This isn't fair!"; or, "Why did this happen?" The hard truth is that I probably did not have any control (or very little control) over what happened. Suffering is the additional layer of RESISTANCE to what is, to the reality of a world controlled by natural forces. The laws of nature dictate that things that are born and come into being, will ultimately sicken and die. There is no escape from that inevitability. Water can quench thirst and can also drown; fire can warm us and can also burn us. Acceptance of the world "as it is" is wisdom. Once we accept the world as it is, our suffering diminishes.
Pain is a natural part of life; suffering is, however, optional. Whenever you are caught in a mental storm, I can assure you that you are caught in suffering, not in pain.The pain of life is usually intense and brief, but it is our language about it that creates the endless rumination and the seemingly endless, turbulent suffering.