Only once one has known real sadness can one feel true happiness.

The statement that only those who have experienced real sadness can feel true happiness is generally agreed on. This is because of the contrasting nature of the two emotions. The terms 'expert' or a 'subject expert' in any area is typically applicable to those who know the good and bad (the extremes) of their art. It is no wonder people often say that you have to know the bad to appreciate the value of good!. The examples supporting this are umpteen and a few of them stand out, Abraham Lincoln, Lance Armstrong, Lionel Messi.
              In support to the statement is the life incident of Abraham Lincoln, the famous president of United States of America. Abraham Lincoln lost in elections, lost his wife and was out of money. He had no reason to continue contesting in elections or to cherish the dream of leading his fellow countrymen. He still held on because he knew he had seen the real sorrow in life, he would be able to reach true happiness in life. He was one of those who believe for a brighter and a happier tomorrow no matter how today is!.
              Buttressing the statement is another life story: Lance Armstrong, a cancer survivor and 7 time Tour De France winner. Lance Armstrong suffered from testicular cancer when he was just 25. The cancer in his life had some serious ramifications. He lost his cycling contract because he was unable to cycle, he spent all his money on the treatment, his girl friend with whom he had been dating for several years had broke up with him. He was forced to take 4 rounds of chemo - sessions (the maximum humans can be administered). This experience he later described as 'living in hell'. But after the cancer was cured, he went on to win 7 consecutive Tour De France cups, which is the hardest cycling race on the planet. He claims that all the trophies that he won after cancer were extra memorable only because he knew life at its worst.
              Consider the case of Lionel Messi, a well known football player who did not have money to eat 3 meals a day. He used to serve tea at a tea stall to live. He too holds a similar opinion on life, success and happiness.
                Similar to the rest of human psychological emotions, we observe that happiness cannot be relished in a proper way until real sorrow has not been faced. In fact, it could be case categorically that something cannot be enjoyed in a true sense unless the opposite of it is also known. Hence, i feel the statement describes a true human applicable paradigm.