|A depiction of "sociology" overlaid on the five main branches of natural science, namely: astronomy, geology, CHNOPSology (biology), physics, and chemistry.|
“It seems that his continued work in physics made the author choose this strange title. He may have noticed that often in natural science, ethical similes are used to bring something nearer that is remote from the region of human knowledge, and so, presumably, he may have wanted to trace the parlance of a chemical simile back to its spiritual origin, all the more so since there is after all just one nature.”
Goethe thus defines "natural science" as the unified study of chemistry, physics, and humanities. German physicist Karl Pearson, likewise, defines “natural science” in an encompassing manner, which he explains via footnote as follows: 
“I use this word—natural science—purposely, for I allow no distinction ultimately between the physical and biological branches of science. A the latter advances, mere descriptions of sequences of sense-impressions are more and more likely to be replaced by formulae describing conceptual motions; such is, indeed, the confessed aim of those somewhat embryonic studies ‘cellular dynamics’ and ‘protoplasmic mechanics’.”
1. Kompridis, Nokolas. (2006). Philosophical Romanticism (pg. 246). Routledge.
2. Pearson, Karl. (1900). The Grammar of Science (pg. 299). Adam and Charles Black.
● Natural science – Wikipedia.