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In rain water, I observed a small red worm and two other kinds of very minute insects; of those of the larger size, I judged that 30,000 together would not equal a coarse sand.

Antonie van Leeuwenhoek

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

Accomplishment Busy Himself Man Thinking
I observed certain animalcules, within whole bodies I saw so quick a motion as to exceed belief; 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

Animalclue Belief Body Certain Internal Land Motion Observe Quick Seen Size Transfer
And I judge that some of these little creatures were above a thousand times smaller than the smallest ones I have ever yet seen, upon the rind of cheese, in wheaten flour, mould, and the like.
ANTONIE VAN LEEUWENHOEK

Cheese Creature Ever Judge Mould Seen Smaller Some Thousand Upon
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

Blood Drive Humidity See Talk Time Water
I’ve never taught one, because if I taught one, I’d have to teach others. I would give myself over to a slavery, whereas I want to stay a free man.
ANTONIE VAN LEEUWENHOEK

Freedom Man Myself Slave Stay Teaching
Among other things, 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

Alternative Among Anmalcule ContrAction Head Moorningm Consist Place Swift Thing
Whenever I found something remarkable, I have thought it my duty to put down my discovery on paper, so that all ingenious people be informed thereof.
ANTONIE VAN LEEUWENHOEK

Discovery Down Duty Found Inform People Remarkable Something
How inscrutable and incomprehensible are the hidden works of Nature!
ANTONIE VAN LEEUWENHOEK

Earth Hide Nature Work
[M]y 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

Chiefly Crave Done Knowledge Men More Praise Pursue Time Work
The 4th sort of creatures… which moved through the 3 former sorts, were incredibly small, and so small in my eye that I judged, that if 100 of them lay [stretched out] one by another, they would not equal the length of a grain of course Sand; and according to this estimate.
ANTONIE VAN LEEUWENHOEK

Creature Equal Eye Grain Hope Incredibly Judge Length Move Sand Small Sort Through
For my part, I hold it equally impossible for a small shellfish to be produced without generation as for a whale to have its origin from the mud.
ANTONIE VAN LEEUWENHOEK

Equality Hold Myself Origin Production Small
Examining this water…I found floating therein divers earthy particles, and some green streaks, spirally wound serpent-wise.
ANTONIE VAN LEEUWENHOEK

Diver Earth Examine Float Found Green Particle Serpent Some Streak Water Wise Wound
And therewithal, 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

Anything Discovery Down Inform might People Put Remarkable
There was discover’d by me a fifth sort, which had near the thickness of the former, but they were almost twice as long. The first time bacteria were observed.
ANTONIE VAN LEEUWENHOEK

Bacteria Discover Fifth First Former Long Observe Sort Thickness Time Twice
This particle I concluded to be the heart.
ANTONIE VAN LEEUWENHOEK

Conclude Heart Particle
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

Believe Goodness Myself Observation Time Trouble