Strangers Drowning : Impossible Idealism, Drastic Choices, and the Urge to Help by Larissa MacFarquhar is a deeply inspiring and thought-provoking book.

Most part of the book consists of a collection of profiles for do-gooders who go to extreme length to help strangers. To some extent, they have chosen to save drowning strangers instead of their own family, which may be unsettling for many people. Thus the book also discusses attacks mounted against do-gooders throughout history.

Many good reviews have already been written about the book. So I will just list a few lessons which I have learned from reading it.

Absolute moral clarity is unattainable and unnecessary

Stephanie Wykstra's (FROM THE POINT OF VIEW OF THE UNIVERSE) is a woman who takes moral questions seriously.

Shortly after she turned thirty, Stephanie Wykstra decided that she no longer believed in unlimited altruism. ... She had grown up with a sense of utter moral clarity, ... but this had gradually withered and rotted ... In her twenties, she embarked on a series of quests, looking for clarity of a different sort ... After the last quest failed, she accepted that she might never know again the unshakable moral certainty she had known as a child.

Just as Stephanie, I had been obsessed by the question "what is the right thing to do" in recent years. However, after reading many moral philosophy, ancient and modern, I still cannot say that I have all the answers.
My conclusions is that there that I will get nothing done if I just keep searching. It is better to do some good with unanswered questions than to do nothing at all.

Helping people should not be the ultimate end

Ittetsu Nemoto (PLEASE REPLY TO ME AS SOON AS POSSIBLE) is Japanese Buddhist priest who dedicated himself to suicide preventions.

Nemoto wanted to help suicidal people talk to each other without awkwardness, and so he created a suicide website. ... People communicated with one another on the site, and they also wrote to him. ... He responded to everyone. He wrote back to all e-mails, and often, when he wrote, a reply would arrive within minutes, and he would reply to the reply. He answered all phone calls, day or night; many came in the night ...

Such a heavy workload took a toll on Ittetsu.

In the fall of 2009, he began to feel a heaviness in his chest. ... Five arteries were blocked; his doctor told him he could die of a heart attack at any time. ... All this time, the e-mails and the phone calls kept coming ... From the hospital, he wrote to his correspondents and told them he was sick. ... They didn’t care that he was sick ... Lying in the hospital, he spent a week crying. ... What was the point?

When he finally recovered, Ittetsu decided to make a change.

He realized that, even if the people he spoke to felt nothing for him, he still wanted something from them. There was the intellectual excitement he felt when he succeeded in analyzing some problem a person had been stuck on. ... And then there was something harder to define, a kind of spiritual thrill in what felt to him ... ... Helping people should be nothing special, he thought. It should be like eating—just something that he did in the course of his life.

Ittetsu's story tells us that helping others itself should not be the end, for the simple reason that it is impossible to fix every problem in the world. If we narrowly aim at alleviate suffering on this planet, we will only be overwhelmed and work ourselves to an early death. To be an sustainable altruist, there must be something in doing good that also helps us.

Be prepared for the bad results

Sue and Hector Badeau (THE CHILDREN OF STRANGERS) is a couple who have great compassion for children in distress.

By the time they were four years out of college and four years married, they had had the two kids and adopted the two kids and thought their family was complete. ... and long before they adopted their last, twenty-second child, eleven years later, the four-child family they had imagined in high school was a distant memory ...

It took them herculean effort to take care of so many kids.
However, when a family is this big, things will go wrong sometimes.

Terrible, painful things happened over the years that they were not able to prevent—three children dead, two in jail, teenage pregnancies, divorces. ...

Reading their story, we may wonder if they have had fewer children, some of these problems could have been avoided. But we will never know the answer.

The lesson here might be this -- Despite their best effort and intension, helping other may have unexpected bad consequences. The do-gooders should not blame themselves if this happens and take well-deserved pride in their effort.