Reviewed by: Habits and Holiness: Ethics, Theology, and Biopsychology by Ezra Sullivan, O.P Craig Steven Titus Habits and Holiness: Ethics, Theology, and Biopsychology. By Ezra Sullivan, O.P. Foreword by Wojciech Giertych, O.P. Washington, D.C.: The Catholic University of America Press, 2021. Pp. xxxii + 575. $34.95 (paper). ISBN 978-0-8132-3329-1. Habits and Holiness is about the human basis for divinely inspired change and flourishing in a person and among friends. In this impressive work of integration, Ezra Sullivan, O.P., addresses the meaning of the ongoing change involved in the acquisition of habitual readiness to flourish. He argues that the moral habits are the most important capacities that underlie good moral action and growth in holiness and that resist evil acts and vices. Placing the neurological, biological, empirical, and psychological sciences in service of philosophical and theological sources, he employs a method and a philosophical anthropology that focus on a multidimensional and teleological understanding of habits and holiness. The book is divided into three parts, each of which focuses on one aspect of the importance of habits in the quest of holiness in the Christian life. The first part is devoted to the biological bases of the habits and dispositions that serve the human acquisition of both virtues and vices. Sullivan calls upon the different disciplines involved in biopsychology to address the behavioral momentum of human habits, using the analysis of what he calls the habit loop (an antecedent trigger or cue, the behavior itself, and a consequent reward) to help understand the foundation of voluntary action according to reason. Sullivan calls these aspects of dispositions “subterranean habits” because they underlie the involuntary (i.e., prerational and preaffective) aspects of universal human nature and particular individual nature (second nature). He presents an extensive study of human nature, dispositions, and instincts, including the cogitative power, which has a special role in prerational cognition and higher-order perceptions. He builds upon Thomas Aquinas’s thought and the distinction between general human nature, which is common to all, and a person’s individual nature, which is a particular expression of human nature. This distinction gives a further basis to account for individuality, diversity, and the providential order. The second part of the book considers habits in the context of a Thomistic approach to freedom and habituation. Habits are distinguished as positive (virtues) or negative (vices). According to the nature of their objects, habits are also distinguished as acquired virtues (both intellectual and moral), or as supernatural, infused, and theological virtues. Of special interest for the spiritual life are the promptings involved in the gifts of the Holy Spirit. These gifts are often ignored or neglected in contemporary theology. They are, however, an important part of Aquinas’s doctrine of dispositions, which interact with the theological and infused virtues. The third part of the book focuses on how habits can be changed, formed, and even “hacked.” Sullivan proposes a model that builds upon self-knowledge [End Page 350] and the input of scientific, philosophical, psychological, ethical, and theological sources. He evaluates techniques for acquiring, developing, and correcting habits. He also discusses how habits become deformed. Of notable interest is his treatment of the habits that serve the virtues of faith, hope, and charity. This approach to habit, virtue, and grace also demonstrates how merit is salient to formed and deformed habits. A full consideration of personal cooperation with habitual grace and with sanctifying grace and the merits of Christ leads to an understanding of how human merit influences human participation in the life of grace. Grace and merit involve work on oneself that is social, that demands friendship for developing habits, and that prepares one to flourish. The most original contribution of Sullivan’s work is its integrative approach. The book provides an engagement of contemporary psychology and personality theory with Aquinas’s classic understanding of the person (i.e., the soul). Sullivan uses the multiple conceptual lenses of philosophical ethics, moral practice, and moral theology, as well as the empirical, biological, and psychological sciences. This method serves better to support and even to refine some of Aquinas’s philosophical anthropology and moral...