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. 我们已失去了一切，可是感谢上帝，我们保住了性命。
"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? 我忘了带午饭钱了，你能给我3美元吗？
No. I'm sorry. I can't spare any, but maybe Jim has some extra money. 不，对不起。我没钱，但吉姆可能有多余的钱。
Nowadays more people have more time to spare for cultural activities, and they can also spare more money for enjoyment. 现在越来越多的人有更多时间从事文化活动，他们也有更多的钱用于消遣。
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，上海建起了许多高楼，你现在几乎认不出这个城市了。
With the improving of living conditions, life span has been considerably extended. 随着生活条件的改善，人的寿命大大地延长了。