The paper discusses the relationship between time and understanding in Heidegger's phenomenological-ontological hermeneutics. Even thanks to an innovative concept of understanding as an open and projecting dimension, Heidegger can reach the qualitative, dynamic and differential concept of time, which is the basis of the Daseinsanalyse in Sein und Zeit. Only if comprehension is meant as a primary phenomenon can time be thought as an ecstatic disclosedness, i.e. an original, ontologically inderivative, unprogrammable non-functionalistic and essential temporality, which always involves and concerns us.