From the Ming novel 《
水浒传》 chapter 36 and circulated widely in Ming-Qing fiction:
踏破铁鞋无觅处,
得来全不费功夫 — 'I wore out iron shoes with no place to find it; when it came, it took no effort at all.' A household couplet in Chinese — the perfect phrase for the experience of searching everywhere and then stumbling onto the thing by accident.