I can see where Walsh’s work must have been helpful to Catholic students and readers in its day and beyond. He catalogues the achievements of the thirteenth century as unique in their creativity and inventiveness. Among the accomplishments of the 1200’s he cites the famous philosophers and the growth of universities, the development of vernacular literature and scientific experimentation, the geographic growth of economy, the education of women, the development of what we would term today “Catholic Charities” [which he credits to the vision of Innocent III], advances in law and representative government [e.g., the Magna Carta], the friars, exploration [Marco Polo], and the magnificence of the great cathedrals and attendant liturgical art and music.
Walsh has done me a favor in providing a platform to look at the 1200’s with a view to the Reformation three centuries down the road. In fact, Walsh was not a professional historian, and his primary purpose in writing—along with satisfying his insatiable curiosity—was to refute Protestant charges about the Catholic Church that were quite common through the twentieth century. Walsh puts forth a fair argument that Catholic Christendom had left a significant heritage to all of history in its thirteenth century achievements. He specifically refutes charges that the Church suppressed scientific knowledge and deliberately contributed to the subservience of women.
Walsh’s book today falls under the heading of apologetics or defense, the reason I was not required to read it in 1970. His apologetic argument is quite understandable because the United States was a predominantly Protestant country awash in anti-Catholicism in 1907 when the author finished this work. The American bishops had only recently mandated that Catholic children—most of whom of strong ethnic identity-- attend parochial schools for their physical and religious safety; the public-school agenda was routinely anti-Catholic, questioning the loyalty of Catholics to the country or the Vatican. In our context here, Protestant opposition to Catholic thought and practices focused upon developments of the medieval era; the Church Luther opposed was in fact the medieval church, not the Church of Paul or Augustine.
However, in the present day The Thirteenth enjoys something of a mild resurgence in conservative Catholic blogsites. I came across this 2009 favorable review of the work, a defense of the author’s thesis against life in our present day. The review is a canonization of the thirteenth century in a way that suggests we would all be better off back then.
The reviewer, and the author, for that matter, both make the amateur’s mistake of skimming across the top of an era and missing the many complications beneath the surface. Just about every topic listed in the author’s table of contents is a two-edged sword where the Church is concerned. The circumstances surrounding the Magna Carta  were profoundly influenced by Pope Innocent III, the age’s most powerful pontiff. The last pope of the thirteenth century, Boniface VIII, was physically overtaken by King Phillip IV of France and died from his ordeal. What Walsh missed in his priorities was a steady decline in the power and regard for the papacy to the degree that the entire machinery of the papacy would be hijacked to France barely into the next century.
The universities would assume much of what we call the “magisterium” or teaching authority of the Church throughout the century and into the next. Thoughtful Catholics looked to Paris and Oxford, and to the teachings of Aquinas and others on matters as diverse as the Immaculate Conception, the morality of war tactics, and particularly the developing body of Church or Canon Law. The burgeoning trade between nations led to the introduction of ancient Greek texts translated and transmitted by Islamic scholars. The expression of doctrinal Catholicism would take the form of Aristotle, for better or worse [except among a body of independent philosophers such as William of Ockham, who was born in the thirteenth century.]
Walsh cites St. Francis of Assisi for his artistic contributions to Church life, notably the introduction of the Christmas creche. But he misses or is ignorant of the century-long struggle for the identity of the Franciscan Order and the deeper question of the role of the Bible in Catholic lay piety. There were numerous groups similar in nature and purpose to Francis’ ideals who carried personal piety beyond the bounds of Church thought and authority, leading to the formalization of the Inquisition under the Dominican Order.
It does make sense to single out the thirteenth century in the sense that a limited number of “terrible” things happened. [In 1978 Barbara Tuchman wrote the best-selling A Distant Mirror: The Calamitous Fourteenth Century; I always wondered why Barnes and Noble did not combine Tuchman’s and Walsh’s books in a boxed set.] When I say that the thirteenth century was relatively calm, I am overlooking Crusade IV and the horrific destruction of Constantinople by the Crusaders; or Crusade V—famous for the meeting of Francis of Assisi and the Sultan—which led to an inglorious Christian defeat. I have said nothing about the destruction of any lasting hopes of Christian reunion between East and West.
The thirteenth century was a remarkable era and certainly an inventive one; it was not exactly the calm before the storm, but those living at century’s end could scarcely imagine what awaited them in the fourteenth, because Tuchman’s term “calamitous” was an understatement.