and sleds are still a-flying
(Wakai toki wa nido nai;
“There is no second youth”)
You only have your youth once, so it’s best to get out there and do stuff wholeheartedly while you still have the time and energy.
Note that this formulation is very broadly applicable and can be read as encouraging the listener to brush up their skills, work and save money, start a business, go on adventures, sow wild oats, experiment with different experiences and lifestyles, and so on and so forth. But apparently an older and longer version has a more specific agenda: it talks about how one’s youth is specifically wasted by going through life without appreciating the wonder of nature and the beauty of the four seasons.
We begin with the adjective 若い (wakai), “young,” preceding but not modifying the noun 時 (toki), “time,” which is marked as the topic of discussion by the particle は (wa). The comment on this topic begins with the number-noun 二度 (nido), elides all particles, and ends with the adjective 無い (nai), “not.”
This phrase comes to us from our friend the Wen Xuan (Japanese 『文選』 = Monzen), an early Chinese literary anthology. On the way it seems to have been referenced (or independently invented) in – and is sometimes attributed to – a number of other works including an ukiyo-zoushi titled 『当世銀持気質』 (Tousei kanemochi katagi), roughly “The modern-day rich-person mindset.” The longer phrase cited in the Definition section is attributed to a Muromachi-era official named Ise Sadachika (伊勢貞親).
This phrase is the wa entry in the Osaka iroha karuta set.
At least one variant phrase exists, replacing 時 with 内 (uchi), “within,” and following 二度 with particle と (to), which changes it from a noun into an adverb.
(“Kenta, mou geemu wo yamete, tomodachi to soto de asonde koi. Wakai toki wa nido nai zo.”
“Tousan, ore, ima, Ken-chan to issho ni tsukutta geemu no hinshitsu wo kakunin suru tame ni tesuto wo shiteru nda. Orera no wakai toki wo muda ni shiteru hazu ga nai.”)
[“Kenta, quit playing that game and go play outside with your friends already. You won’t get to be young a second time.”
“Dad, right now I’m doing a quality-assurance test for the game Ken-chan and I made together. I don’t think we’re wasting our youth.”]