Quotes from Antonie van Leeuwenhoek

Man has always to be busy with his thoughts if anything is to be accomplished.

If we now plainly perceive that the passage of the blood from the arteries into the veins of the tadpole is not performed in any other than those vessels, which are so minute as only to admit the passage of a single globule at a time, we may conclude that the same is performed in like manner in our own bodies and in those of other animals.

A man has always to be busy with his thoughts if anything is to be accomplished.