I had been spared, but by what? Mercy? A short attention span? Hunger? (Para. 26)
Meaning: My life had been saved, but what save my life? Was it mercy? Was their attention span too short? Or was it their hunger that saved my life?
If a person is spared, he is not harmed, although someone or something threatened him or harmed other people. For example,
We have lost everything, but thank God, our lives have been spared. 我們已失去了一切，可是感謝上帝，我們保住了性命。
"Spare" can be also used in the sense of "afford to give".
I forgot to bring any money for lunch. Can you spare three dollars? 我忘了帶午飯錢了，你能給我3美元嗎？
No. I'm sorry. I can't spare any, but maybe Jim has some extra money. 不，對不起。我沒錢，但吉姆可能有多余的錢。
Nowadays more people have more time to spare for cultural activities, and they can also spare more money for enjoyment. 現在越來越多的人有更多時間從事文化活動，他們也有更多的錢用于消遣。
span: n. the full time for which anything lasts
Over a span of 5 years, a lot of high-rises have been built in Shanghai; you can hardly identify the city now. 在5年中，上海建起了許多高樓，你現在幾乎認不出這個城市了。
With the improving of living conditions, life span has been considerably extended. 隨著生活條件的改善，人的壽命大大地延長了。