This paper presents a version of a defense of the epistemic significance of insight (as a kind of intuition) in the process of human knowing. The position of Bernard Lonergan (1904-1984) laid out in 'Insight: A Study of Human Understanding' (1957) is discussed. The relations between insight and the basic cognitional activities are analyzed. The analysis answers the question of the epistemic functions of insight in the process of acquiring knowledge. Insight accompanies all cognitional activities. In particular, it is essential in those activities that are crucial from the point of view of knowledge generation and evaluation. The way that insight functions as a component of central cognitional activities - for example in generalization and justification - allows us to argue that it is an essential and indispensable element of knowing. The paper consists of six sections: 1. Preliminary remarks; 2. The cognitional process as the object of study for cognitional theory; 3. The notion of insight and its properties; 4. The dynamic structure of knowing; 5. Functions of insight in the cognitional process - (a) the level of experience (b) the level of intelligence (c) the level of judgment. 6. Final remarks.