This paper seeks to explore the cognitive performance of imagination [φαντασία] in building the starting point of scientific explanations. I wish to indicate how φαντασία plays a rol in the construction of meaningful wholes which allow the emergence of conceptual horizons for scientific theories. With this in mind, I turn first to the traditional doctrine of the knowledge of principles in Posterior Analytics II, 19. Secondly, I will discuss De Anima 402b16-403a2, a text which I believe sheds light on this issue. In conclusion, I point out some overlaps between the role of imagination in understanding theoretical principles and the role its plays in shaping the ultimate goal of human life.