Hans Urs von Balthasar was a Swiss theologian and Catholic priest who is considered one of the most important Catholic theologians of the 20th century. With Joseph Ratzinger and Henri de Lubac, he founded the theological journal Communio. Over the course of his life, he authored 85 books, over 500 articles and essays, and almost 100 translations. He is known for his 15-volume trilogy on beauty, goodness (Theo-Drama), and truth (Theo-Logic).

Charles Pierre Péguy was a French poet, essayist, and editor. His two main philosophies were socialism and nationalism; by 1908 at the latest, after years of uneasy agnosticism, he had become a believing Roman Catholic. From that time, Catholicism strongly influenced his works.