Under the aegis of Franz Bopp (1791-1867) a new study of language was shaped in the 19th century namely historical and comparative linguistics. The new way of approaching language was decidedly more in spirit with approaches known in the natural sciences. It is fair to say that this way of language study was the forerunner of what we now know as general linguistics. At least Bopp was the first person to occupy a chair in ‘Allgemeine Sprachkunde’ as early as 1821. In my talk I will trace direct influences of the natural sciences on comparative philology and vice versa. These were visible both in methodological principles as in explanatory patterns. I will show what these patterns and principles where by looking at the contributions of both Bopp and Grimm, the main actors of the 1st generation of comparative linguists. Among the 2nd generation considerable difference of opinion came about whether linguistics should be (or become) a natural science or remain strong ties to the more culturally oriented philology and thus remain part of the humanities. This tension was already present in the work of Bopp itself but rose to the surface only in debates between prominent members of the second generation with Schleicher and Müller on the one side and Curtius and Whitney on the other side. I will consider what the alignment to either the natural sciences or to the humanities meant for the comparative study of language and how this choice shaped the further development of the principles and patterns the 1st generation had begun to create. The study of this episode is interesting for at least two reasons. First it serves the broader theme of the humanities as knowledge making disciplines. Second it provides insight in interdisciplinary relations across the natural sciences as well as the humanities in the 19th century. This is an understudied area of research and including the humanities in it provides a useful check on the natural science dominated historiography of the period.