I've spent more time than many will believe [making microscopic observations], but I've done them with joy, and I've taken no notice those who have said why take so much trouble and what good is it?

Antonie van Leeuwenhoek

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

Antonie van Leeuwenhoek

I have divers times endeavoured to see and to know, what parts the Blood consists of; and at length I have observ'd, taking some Blood out of my own hand, that it consists of small round globuls driven through a Crystalline humidity or water.

Antonie van Leeuwenhoek

Whenever I found out anything remarkable, I have thought it my duty to put down my discovery on paper, so that all ingenious people might be informed thereof.

Antonie van Leeuwenhoek

My work, which I’ve done for a long time, was not pursued in order to gain the praise I now enjoy, but chiefly from a craving after knowledge, which I notice resides in me more than in most other men.

Antonie van Leeuwenhoek

I observed certain animalcules, within whole bodies I saw so quick a motion as to exceed belief.

Antonie van Leeuwenhoek

I saw this vast number of animalcules not all through the semen, but only in the liquid matter adhering to the thicker part.

Antonie van Leeuwenhoek

I saw in the body of one of these animalcules a bright and round corpuscle, placed near the head, and in which a very wonderful swift motion was to be seen, consisting of an alternate extension and contraction.

Antonie van Leeuwenhoek

They were about the size of a large grain of sand, and their bodies being transparent, that the internal motion could plainly be seen.

Antonie van Leeuwenhoek

In the year 1657 I discovered very small living creatures in rain water.

Antonie van Leeuwenhoek