My only supporter and comrade-in-arms was Georg Helm, who had endeavored to formulate an energetic conception of science before me and had presented his results in a treatise [Die Lehre von der Energie] exhibiting great independence of thought. But we were separated by his aversion to a realistic conception of energy. Consequently, each of us considered the other only a half ally, toward whom an attitude of caution was necessary.

In the first quarter of the nineteenth century the experimental proof for the interdependence of the composition and properties of chemical compounds resulted in the theory that they are mutually related, so that like composition governs like properties, and conversely.

We know from biology that new forms of organisms simulate their primitive form as closely as possible at first, even though obliged to exist under changed internal and external conditions.

In specific circumstances the period of aging decline can set in earlier in a particular organ than in the organism as a whole which, in a certain general or theoretical sense, is left a cripple or invalid.

The individual organs follow the same pattern as the whole organism, i.e. they have their period of growth, of stationary, maximum activity and then of aging decline.

For, with pure water the inversion of cane sugar scarcely proceeds and subsequently it required very thorough, difficult studies before this effect and its order of magnitude were established.

The development of a rational view of the nature of catalysis was thus absolutely dependent on the creation of the concept of the rate of chemical reaction.