There is not a "pure" science. By this I mean that physics impinges on astronomy, on the one hand, and chemistry and biology on the other. And not only does each support neighbors, but derives sustenance from them. The same can be said of chemistry. Biology is, perhaps, the example par excellence today of an "impure" Science.

In: Shirley Thomas, Men of Space. Profiles of the Scientists Who Probe for Life in Space, (Volume 6)