No one has been a greater botanist or zoologist. No one has written more books, more correctly, more methodically, from personal experience. No one has more completely changed a whole science and started a new epoch.

Natural bodies are divided into three kingdomes of nature: viz. the mineral, vegetable, and animal kingdoms. Minerals grow, Plants grow and live, Animals grow, live, and have feeling.

A herbarium is better than any illustration; every botanist should make one.

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.

It is not God, but people themselves who shorten their lives by not keeping physically fit.

The plant kingdom covers the entire earth, offering our senses great pleasure and the delights of summer.

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