"Beautiful Souls," by Eyal Press Paul Grüninger, a Swiss police commander, had a simple explanation for why he broke the law to help Jewish refugees flee Austria in 1938. His daughter remembered that he would repeat the words "I could do nothing else." It is a humble answer, as if to say that anyone would have done the same. Paul Grüninger was jailed for helping Jewish refugees enter Switzerland. Saying No, Breaking Ranks, and Heeding the Voice of Conscience in Dark Times By Eyal Press Farrar, Straus & Giroux. $24. Except that most Swiss police officers didn't: they turned the refugees away, as the law required. Grüninger made a choice, and it was certainly not the expected one. He did not fit the image of a resister. He was not a political activist and did not have a history of rebellion. He had a family to protect and provide for. He had taken an oath to uphold the law, and he considered himself faithful to his country. When the authorities discovered that he had falsified the documents of Jews, he became a pariah. So why did he disobey his orders? That is the question that Eyal Press asks in "Beautiful Souls." It is not a book of moral philosophy. Press is a journalist, and he is interested in how moral problems play out in particular lives. To that end, he relates the experiences of Grüninger and three others: a Serb who saved the lives of Croats by lying about their ethnic identity; an Israeli soldier from an elite unit who refused to serve in the occupied territories; and a financial industry whistle-blower. Press is not simply storytelling, however. He splices his case studies with brief accounts of other dissenters, along with insights drawn from sociology, political theory, history, neuroscience, psychology, fiction and philosophy. Press examines his subjects carefully, alert to the different personalities and circumstances of each individual. He weighs the role of prejudice, idealism and community. He explores the "element of reciprocity" in one case and the "anxiety of responsibility" in another, sees the importance of "mutual support" and discusses the frustrations of being ignored. He reads about oxytocin receptors; he studies David Hume. He makes modest conclusions. I don't mean that as criticism. If Press made more comprehensive claims, I wouldn't trust him. It's no more possible to explain an act of conscience than it is to dissect a dream. We often use the word "conscience" when we don't know what other word to use. When Grüninger said he "could do nothing else," he may have been deflecting judgment, or he may not have been able to describe his sense of compulsion any better, his feeling that he didn't have a choice when he clearly did. "Conscience" is indefinable. It can be indefensible, too: An act of conscience describes an action motivated by loyalty to a conviction, but it usually requires the defiance of other loyalties. It can mean turning away from your family, or your country, or your job, or even your sense of self. Press's real achievement in this short book is not in his research or analysis, but in his refusal to flinch from that disquieting fact. Though Press clearly admires his characters, and wants readers to find them inspiring, he can see how their actions can create conflict and their personalities grate. "If I knew only Thoreau," Ralph Waldo Emerson wrote of his friend Henry, "I should think cooperation of good men impossible." The conflicts can be benign. Thoreau plants his beans, refuses to pay the tax collector, spends a night in jail, writes a masterpiece. But moral convictions can lead to disengagement from civic life, or sometimes even wars. A conscience can be used to justify anything, even heinous crimes. It can lead a person to protect his purity at the cost of harming other people. As Press acknowledges, what you might call fanaticism I might call justice. One Israeli solder refuses to serve in the occupied territories because of injustices perpetrated against Palestinians; another refuses to remove Jewish settlers because they are Jewish. Both men appeal to their consciences. "Measured by depth and sincerity of conviction, perhaps there wasn't much difference between left- and right-wing refuseniks in the Israeli Army," Press writes. Measured by moral content, there clearly was. To distinguish between them, Press cites "the standard Adam Smith might have proposed": the "stretch" of their "moral imaginations," which he describes as the ability to sympathize with those who suffer. Louisa Thomas is the author of "Conscience: Two Soldiers, Two Pacifists, One Family - a Test of Will and Faith in World War I."