What's the origin of the Chinese Farmer story? Alan Watts told The Story of the Chinese Farmer, which is also sometimes found under the title Maybe. It appears that he told this story sometime between 1960-1969, since it was published in Watts, A. (2011). Eastern wisdom, modern life: Collected talks: 1960-1969. New World Library.

Is there any history of this story before Watts? Is there a similar story that it might have been based upon? On the other hand, has some scholar researched this question and concluded that Watts wrote it himself?
There may be earlier renditions, but this story is in the Huainanzi compiled around 139 BCE:


  近塞上之人有善術者，馬無故亡而入胡，人皆弔之 。其父曰：此何遽不為福乎
  
  Among the people who lived close to the border, there was a man who
  led a righteous life. Without reason, his horse escaped, and fled into
  barbarian territory. Everyone pitied him, but the old man said : "what
  makes you think this is not a good thing?"
  
  居數月，其馬將胡駿馬而歸，人皆賀之。其父曰：此何遽不能為禍乎
  
  Several months later, his horse returned, accompanied by a superb
  barbarian stallion. Everyone congratulated him. But the old man said:
  "what makes you think this is cannot be a bad thing?"
  
  家富良馬，其子好騎，墮而折其髀，人皆弔之。其父曰：此何遽不為福乎
  
  The family was richer from a good horse, his son enjoyed riding it. He
  fell and broke his hip. Everyone pitied him, but the old man said:
  "what makes you think this is not a good thing!"
  
  居一年，胡人大入塞，丁壯者引弦而戰，近塞之人，死者十九，此獨以跛之故，父子相保
  
  One year later, a large party of barbarians entered the border. All
  the valid men drew their bows and went to battle. From the people
  living around the border, nine out of ten died. But just because he
  was lame, the old man and his son were both spared.
  
  故福之為禍，禍之為福，化不可極，深不可測也。
  
  Thence, good fortune turns into bad fortune, and bad fortune turns
  into good fortune. These changes never reach an end, their complexity
  can never be fathomed.