This book is the best book ever written on Tertullian in English. The summaries of the content of each work are full of life, and Tertullian himself lives in these pages.
Much of the book is taken up with a detailed and systematic exploration of what we think we know about the man and the world he lived in. Barnes wrote this in 1971, under the influence of 1960's revisionism, and his conclusions have since been revised (see the appendix written in 1985 in which he discusses this). But simply reading how he goes about evaluating the data, and how he refers to it, will be a liberal education for most people.
The humanities does not have to consist merely of people promoting their prejudices. It can be solidly fact-based and data-driven. Barnes provides this marvellous example of a Roman historian discussing a difficult subject in the most objective manner possible.