Thomas Aquinas connects theology and philosophy by employing reason to support religious dogmas, which was revolutionary at the time. He integrates Aristotle’s philosophy, which is based on sensory experience, into Christian doctrine, despite the threat this posed to faith. Thomas Aquinas argued against the idea of two truths (faith and reason) and emphasized that there is only one divine truth, which can be partially grasped through reason and revelation. For him, the true is a mode of being of things that reveals itself to our intellect, and he formulated a correspondence theory of truth. Thomas Aquinas regarded the true as that aspect of being which is oriented toward the human intellect. This distinction between the true and truth highlights that there are aspects of being that our intellect may not be able to grasp. Aristotle and the Stoics influenced this perspective, considering facts and things as separate entities. Thomas Aquinas emphasized that the true lies in things, while truth is a property of statements. His ontology and epistemology stress that things are knowable to us through their form and their relation to the divine intellect. Thomas further argued that the existence of God is necessary to ensure the coherence of our knowledge, and that God functions as the measure of all things. In the doctrine of transcendentals, which Thomas further developed, being is described through fundamental concepts such as “one,” “something,” and “other,” which shape our intellect. Despite this complex philosophical argumentation, the central assumption remains that human reason and being are ultimately anchored in God. The chapter discusses the problems and implications of the doctrine of transcendentals. This leads to a double impasse: the supposed failure of metaphysics and the rise of the philosophy of the subject. The doctrine of transcendentals attempts to explain how our intellect can know a reality independent of itself by positing an intelligibility in things. However, this leads to a possible misunderstanding that epistemology and ontology are essentially the same, which has discredited metaphysics as speculation without empirical basis. The doctrine of transcendentals calls for humility in thought: since we cannot be certain how our thinking corresponds to reality, we should restrict ourselves to the investigation of thought itself. This, however, raises the question of whether we thereby learn something about reality or only about our own intellect. Nicholas of Cusa argued that our intellect can never grasp the perfect essence of being, but can only approach it. He emphasized the insurmountability of the difference between the finite human intellect and infinite being. For him, the essence of the infinite remains hidden from the human intellect, which points to the limitations of our understanding. William of Ockham, on the other hand, saw truth as a property of sentences and not as something in things themselves. He emphasized the independence of truth from linguistic structure and pointed out that our language does not mirror the structure of the world, but only shows meaning in its use. This led to the realization that the truth of states of affairs exists independently of our language and our judgments. Ultimately, the chapter emphasizes that the cognitive capacity of the intellect itself must be examined in order to understand how we can know reality. This marks a transition from metaphysics to epistemology, as later developed by Kant and other philosophers.