What is the English equivalent to the Chinese/Japanese saying, “塞翁失馬— Life is like Old Sai’s horse”?

proverbs

Dr. Shinya Yamanaka, 2012 Nobel Prize winner in Physiology or Medicine, the initiator of all-around (iPS) cells told a recently-held public symposium, quote:

“I’m often asked by many people: ‘You are happy that you've won the Nobel Prize, aren’t you?’ But I tell them that everything in life is just like 'Saioh ga uma' (塞翁が馬) – Old Sai’s horse. I was unsuccessful as an orthopedic surgeon, but luckily I found my way in molecular biology." – The Asahi, Oct.4, 2014 issue

“Life is like Old Sai’s horse” is a popular Japanese saying, which is based on the story described in Chinese classic literature written by 准南子- Huai nan zi, the ancient Chinese monarch of Huian nam in circ. BC 135.

The story begins when a horse kept by an old man living near a fort (塞翁) ran away one day. All the neighbors came to console the old man, but he told them not to worry. Ｍonths later, Old Sai's horse came back, accompanied by a faster horse. Old Sai’s son loved horse riding. He fell off and broke a leg one day while riding the faster horse. The son became lame. Villagers consoled Old Sai for his son's misfortune. But Old Sai said, “Don’t worry. There’ll be a good day after a bad day.” A year later, the village was attacked by the Hu Country's army, and the fort was destroyed. All the young men of the village were called to the military. Nine out of ten of them died during the war. Old Sai’s son was exempted from conscription because he was lame, so he was unharmed. The story goes on and on describing the happenings of a thread of fortune and misfortune of his family in turn.

So when we say “It’s Saioh ga uma -塞翁が馬(塞翁失馬)” in Japanese (Chinese), we mean that life changes, happiness (success) and unhappiness (failure) rotate. We needn’t to be too glad and too sad at each instance.

Though “the ebb and flow” occurs to my mind as a possibility, I’m not sure of whether it fits the concept. Are there more suitable English equivalents to “Old Sai’s horse”?

Solution 1:

Life is swings and roundabouts

This is a shortened version of the fairground proverb 'What you lose on the swings you win on the roundabouts', current from the beginning of the twentieth century in various forms. It is used to mean that things will balance out in the end.

^{Source: Penguin Dictionary of Cliches}

(British & Australian) also what you lose on the swings, you gain on the roundabouts (British & Australian)
We fell out but, hey ho, it's swings and roundabouts and it's a new gaffer now, a new year, so hopefully I can kick on

^{Source: TFD}

A more recent aphorism, which became famous thanks to the 1994 film Forrest Gump, and is known in both the UK and across the Atlantic.

Life is like a box of chocolates

"Mama always said life was like a box of chocolates. You never know what you're gonna get."

Interestingly, Wiktionary says it first appeared in the 1987 Japanese novel Norwegian Wood by Haruki Murakami, following its huge success the novel was translated in English and published two years later.

"Just remember, life is like a box of chocolates." ... "You know, they've got these chocolate assortments, and you like some but you don't like others? And you eat all the ones you like, and the only ones left are the ones you don't like as much? I always think about that when something painful comes up.