The disciples of St Thomas Aquinas have organized their enquiries in diverse ways throughout the history of Thomism. The surge of reinvigorated interest in Thomas Aquinas following Leo XIII’s Aeterni Patris inspired a wide variety of purported types of Thomism in the twentieth century. What should Thomists of the twenty-first century learn from their inheritance of past centuries of Thomism? How can they take up Leo XIII’s call vetera novis augere et perficere. I aim to address two issues in this essay. First, to identify a more principled demarcation of approaches to Thomistic enquiry, which eschews the commonplace but problematic and merely sociological classifications of the last century’s ‘schools’ of Thomism. I argue that a more principled and agenda-setting criteria distinguishes “defensive-constructive commentary Thomism” and “tradition-constituted-enquiry Thomism”. The first stresses fidelity to the conclusions found in careful readings of Aquinas’s texts. The second emphasizes fidelity to Aquinas’s systematic forms of enquiry directed to the truth. Second, I then probe the resources these two forms of Thomism have for addressing the epistemological crises facing Thomism, focusing on those concerning how to engage the nova of the sciences and rival philosophical traditions.