Life is filled with disappointments. This is an inevitable and inescapable truth. If at the end of the day you can sit down have a discussion with yourself and decide that you are truly satisfied then you have already died. You have become stagnant. You are a cut flower. There is no longer a reason for you to live other than to witness a decline..
First off, in order to understand such bold statements we must elaborate a bit. Let's start with defining the word "satisfy"
Satisfy: one definition is a simple one - to fulfill.
If one finds themselves entirely satisfied in life then they have fulfilled all meaning and purpose of being.
Life tells us that we will or at the least SHOULD NEVER be satisfied, with anything. This does not deem mankind be set down a path of eternal bitterness. Rather, it frees us up to feeling more accomplished through the lack of expectation. When I take an image and I'm wholly existing in the moment once the image is revealed all feels right and I'm satisfied...until the evening when I've let the image sit and it becomes obsolete. However, it has not failed to achieve any preconceived criteria and therefore it is not a true failure. I can still look at it and feel a sense that everything is correct with the image but what follows is a sense that that which is present could be taken a step further.
The United States' Air Force used to have the phrase "Aim High" included in their motto. This is an endearing sentiment towards the idea that yes, we will always fall short of our true goals. Partially because not until we arrive at an outcome do we realize it has failed and while other times it is because to reach our goal is to finish, to satisfy, to fulfill. I'm not preaching the idea that it's alright to fail, or to be satisfied with honest failure. Rather, I'm speaking about always setting your goals higher than you think you can achieve, aiming you mark higher than you think you can hit. More than likely you will achieve something great.
In archery the goal is to shoot an arrow at a target, landing it as near to the center as you can, and then repeating it. Due to the laws of gravity every object is being pulled towards the Earth's center at approximately 9.81 m/s^2. In life there are always forces working against you, demanding more from you and in the end, above all of them there must be you demanding even more. You are the archer, the arrow, and the target determining your level of success.
American playwrite Arthur Miller wrote an essay entitled Tragedy and the Common Man published in nineteen forty-nine. In his essay there is a brilliant line in which he discusses man's most beautiful quality which is emphasized in the writings of tragic literature and dramatic performances. We strive till the end of our days to realize ourselves. We search for that satisfaction, that fulfillment of life and we constantly fail. What do we do when we fail though? We continue, having realized our failure and we continue on past it. Maybe we keep the knowledge of it present with us at times but we insatiably persist towards self realization.
Line: "In the tragic view the need of man to wholly realize himself is the only fixed star, and whatever it is that hedges his nature and lowers it is ripe for attack and examination."
P.S. In this post I've included several links, some of which lead to pages pertaining to the physics behind the flight of an arrow or why gravity is expressed as 9.81 m/s^2.
Shakespear's Othello, Hamlet, Macbeth, and King Lear (Click here for amazon link - as low as $0.74)
Death of a Salesman By Arthur Miller
A quick 'Google' or 'Bing' search of Greek Tragedies will inundate you with suggestions.