Nature's economy shall be the base for our own, for it is immutable, but ours is secondary. An economist without knowledge of nature is therefore like a physicist without knowledge of mathematics.

As one sits here in summertime and listens to the cuckoo and all the other bird songs, the crackling and buzzing of insects, as one gazes at the shining colors of flowers, doth one become dumbstruck before the Kingdom of the Creator.

The first step in wisdom is to know the things themselves; this notion consists in having a true idea of the objects; objects are distinguished and known by classifying them methodically and giving them appropriate names. Therefore, classification and name-giving will be the foundation of our science.

The names of the plants ought to be stable [certa], consequently they should be given to stable genera.

If a tree dies, plant another in its place.

In natural science the principles of truth ought to be confirmed by observation.

When all the thoughts are concerning one thing and the person loses interest in other things, the melancholy begins.