All thoughts start from emotions.

There is no result in nature without a cause; understand the cause and you will have no need of the experiment.

I roamed the countryside searching for answers to things I did not understand.

I'm not contented to capture the world. I want to change it.

... we might say that the earth has a spirit of growth; that its flesh is the soil, its bones the arrangement and connection of the rocks of which the mountains are composed, its cartilage the tufa, and its blood the springs of water.

Learning never exhausts the mind.

It vexes me greatly that having to earn my living has forced me to interrupt the work and to attend to small matters.