塞翁が馬 is the old Japanese saying of a Chinese philosopher Laozi(老子)'s story of an old farmer who lost his horse. The contemporary Japanese would use の instead of が for this proverb. But anyway, I head this story when I was a kid from my father. I still do not know the actual title for this story in the English speaking countries today. The other day I found this story was taught in one of the Stwart Wilde's lectures. Here is the link.
The story starts from 20:40:15. The story is the allegorical example with regard to the #13, the acceptance, in the Infinite Self 33 Steps.