The question, "Why a transcendental anthropology?" entails already having in someway attained the answer to the question, and yet it also calls for a justification not only of the answer, but of the question itself. In this short work, the Spanish philosopher Leonardo Polo (1926-2013) presents his proposal of a transcendental anthropology and seeks to provide historical and philosophical reasons that make such a proposal timely and fitting for the present historical situation of philosophy. Polo's proposal makes use of the philosophical method that he calls theabandonment of the mental limit. When applied to the study of the human person, the result is a transcendental anthropology that expands the classical doctrine of the transcendentals to include anthropological transcendentals and is capable of critically engaging modern and contemporary philosophy, thus correcting its errors and incorporating its deepest insights into itself.