This 98th entry in the Historical Series of the Reformed Church in America is the definitive biography of Paul de Kruif whose life left intact the basic Christian tenet of service to others, biblically expressed: love thy neighbor. His life involved heavy drinking that led him to AA and, from there, back to religion and prayer. De Kruif's vocation as publicist on behalf of public health was in the forefront of the science of medicine. His professional understanding as a microbiologist, combined with his gift for lucid, compelling prose, made him one whose impact on the health of America could be argued as unparalleled.