The aim in this paper is simply to sketch some basic characteristics of the concepts of mature and immature science. In other words, my aim is to show the importance of these concepts for two purposes that every historian of science has sometime or other to deal with: firstly, the aforementioned concepts are useful for the understanding of great scientific changes or revolutions. (This is particularly true for the historian concerned with the transition from medieval science to the new scientific (...) universe of the 17th century); secondly, it seems possible to me that these concepts might give us the key to the understanding of the interaction between internal and external factors in science’s historical development. Furthermore, I think that we could define mature and immature science in a way that permits us to include external factors in our rational reconstructions without having to give up a criterial theory of scientific rationality. -/- . (shrink)