The search for keys under streetlights has ancient Arab origins parable. A man was looking for something under a lamppost in a park. A person passing by asked the man what he was looking for. The man said, “I lost my house key and I am looking for it. The passerby felt sorry for him and searched with him for a while, but could not find the key. The passerby then asked the man if he had really lost his keys here. The man replied in a nonchalant manner, “No, I didn’t lose my keys. No, I lost the key over there in the dark, but it’s too dark to see anything over there, so I’m looking over here where the light is shining. Finding keys under a streetlamp - Wikipedia
This page is auto-translated from /nishio/街灯の下で鍵を探す using DeepL. If you looks something interesting but the auto-translated English is not good enough to understand it, feel free to let me know at @nishio_en. I’m very happy to spread my thought to non-Japanese readers.