使用 be unable to + 动词原形结构表达能力缺失，结合 a single thing 的强调用法，增强了语气的绝对性和戏剧性效果。
An old woman, having lost the use of her eyes, called in a physician to heal them and made the following agreement in the presence of witnesses:
That if he should cure her blindness, she would pay him a sum of money; but if her infirmity remained, she would owe him nothing.
After the agreement was made, the physician applied his salve to her eyes time and again. However, on every visit, he took away something, stealing all her property little by little.
Once he had stripped her of all her possessions, he declared that he had healed her and demanded the promised payment.
The old woman, upon recovering her sight and finding her house empty of goods, refused to give him anything.
The physician insisted on his claim, and when she continued to refuse, he summoned her before the judge.
Standing up in court, the old woman argued: "The man speaks the truth in one respect, for I did promise to give him a sum of money if I should recover my sight. However, if I remained blind, I was to give him nothing.
Now he declares that I am healed, but I affirm that I am still blind; for when I lost my sight, I saw various chattels and valuable goods in my house. But now, though he swears I am cured of my blindness, I am unable to see a single thing in it."
一位老妇人双目失明，便请了一位医生来治疗，并在见证人面前与他达成了如下协议：
如果医生能治好她的失明，她将支付一笔钱；但如果她的视力没有恢复，她则无需支付任何费用。
协议达成后，医生一次又一次地为她涂抹眼药。然而，在每次来访时，他都悄悄拿走一些东西，一点点偷光了她的所有财产。
当老妇人的财物被搜刮一空后，医生宣称治愈了她的眼睛，并要求支付约定的报酬。
老妇人重见光明后，发现家中已无一物，于是拒绝支付任何费用。
医生坚持索要酬劳，见老妇人仍拒不支付，便将她告上了法庭。
在法庭上，老妇人陈述道：“这位医生说的话有一部分是事实，因为我确实承诺过，如果我的视力恢复，就会给他一笔钱；但如果我继续失明，我就无需支付分文。
现在他声称我病好了，但我却坚持认为我依然是盲的。因为在我失明时，我看见家里有许多家具和贵重物品；可如今，尽管他发誓说我的失明已愈，我却看不见其中任何东西。”