What struck me most in England was the perception that only those works which have a practical tendency awake attention and command respect, while the purely scientific, which possess far greater merit are almost unknown. And yet the latter are the proper source from which the others flow. Practice alone can never lead to the discovery of a truth or a principle. In Germany it is quite the contrary. Here in the eyes of scientific men no value, or at least but a trifling one, is placed upon the practical results. The enrichment of science is alone considered worthy attention.

The progress of mankind is due exclusively to the progress of natural sciences, not to morals, religion or philosophy.

Only about seventy years ago was chemistry, like a grain of seed from a ripe fruit, separated from the other physical sciences. With Black, Cavendish and Priestley, its new era began. Medicine, pharmacy, and the useful arts, had prepared the soil upon which this seed was to germinate and to flourish.

The more fodder, the more flesh; the more flesh, the more manure; the more manure, the more grain.

We may fairly judge of the commercial prosperity of a country from the amount of sulphuric acid it consumes.

A fact acquires its true and full value only through the idea which is developed from it.

A manure containing several ingredients acts in this wise: The effect of all of them in the soil accommodates itself to that one among them which, in comparison to the wants of the plant, is present in the smallest quantity.