The predominant understanding of St. Thomas’s account of the natural law to date has been that it is basically philosophical in character. In Thomas Aquinas’s Cruciform Theology of the Natural Law, Kevin E. O’Reilly, OP, argues that Thomas’s construal of the natural law is, on the contrary, thoroughly theological in its inspiration. In order to establish this point the author first unpacks the significance of the scriptural quotations employed by Thomas in his very first article devoted to the natural law (ST I-II, q. 91, a. 2). Exegesis of one of those quotations, namely Ps. 4:6 – "Offer up the sacrifice of justice" – intimates that the degree to which one grasps the demands of the natural law is intimately bound up with the extent to which one is conformed to the Crucified Christ. Consideration of the notion that the natural law is the participation of the eternal law in the rational creature yields the same conclusion. Thus, while the eternal law pertains to God’s essence, it is nevertheless expressed by and therefore appropriated to the Word uttered by the Father. This Word is the divine Wisdom ultimately disclosed on the Cross. It becomes apparent that the eternal law is thus cruciform in nature. So too is the natural law as a cognitive participation therein. This cognitive participation engages the life of faith and charity as well as the Gifts of the Holy Spirit. Examination of Thomas’s account of the three degrees of charity as well as his treatment of the Gifts of the Holy Spirit and the beatitudes that are correlated with them underscores the important role that the dynamics of cruciformity play in illuminating the demands of the natural law. Cruciformity and moral illumination are intimately connected.