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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

Ten hundred thousand of them could not equal the dimensions of a grain of such course Sand.
ANTONIE VAN LEEUWENHOEK

Course Dimension Equal Grainm Such Hundred Thousand Sand Ten
The 31th of May, I perceived in the same water more of those Animals, as also some that were somewhat bigger.
ANTONIE VAN LEEUWENHOEK

Also Animal Bigger May More Perceive Same Somewhat Water
For my part, I would say that the male sperm and seeds of plants have been penetrated so far that there is nothing further to discover in this great secret, but I could err in my opinion.
ANTONIE VAN LEEUWENHOEK

Biology Discover Errors Greatness Myself Opinion Plant Science Secret
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

Discover Information People Remark Responsibility Thinking
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
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 Done Good Joy Make Microscopic More Much Observation Spent Time Trouble
[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
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

Equality Judgement Kind Myself Rain Togetherness Water Worm
Man has always to be busy with his thoughts if anything is to be accomplished.
ANTONIE VAN LEEUWENHOEK

Accomplishment Busy Himself Man Thinking
How little do we discover in comparison of those things which now are and forever will be hidden from our sight? The whole of which I am fully persuaded no one will ever be able to dive into, and to explain their causes and effects.
ANTONIE VAN LEEUWENHOEK

Comparison Discover Explanation Forever Hide Myself Ourselves Sight
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
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

Adhere Animalcule Liquid Matter Number Part Saw Semen Thicker Through Vast
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
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
In the year 1657 I discovered very small living creatures in rain water.
ANTONIE VAN LEEUWENHOEK

Creature Discover Live Rain Water
Just as the supposed number may differ from the true number by fully 100, 150, or even 200 in a flock of 600 sheep, so may I be even more out of my reckoning in the case of these very little animalcules.
ANTONIE VAN LEEUWENHOEK

Animal Difference Myself Number True
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
This particle I concluded to be the heart.
ANTONIE VAN LEEUWENHOEK

Conclude Heart Particle
The whole circumference of each of these streaks was about the thickness of a hair of one’s head. … all consisted of very small green globules joined together: and there were very many small green globules as well. [The earliest recorded observation of the common green alga Spyrogyra.]
ANTONIE VAN LEEUWENHOEK

Circumstance Consist Each Other Examining Globule Green Small Well Whole
For, the circumference of one of these little Animals in water, is not so big as the thickness of a hair in a Cheese-mite.
ANTONIE VAN LEEUWENHOEK

Big Cheese Circumstance Mite One Thickness Water
Man comes not from an egg but from an animalcule that is found in male sperm.
ANTONIE VAN LEEUWENHOEK

Animal Biology Born Man Science
I have often endeavoured to view the circulation of the blood in terrestrial animals, but without success, by reason that no parts of their bodies were sufficiently transparent.
ANTONIE VAN LEEUWENHOEK

Animal Blood Body Enough Success View
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 Consist Crystalline Diver Driven Endeavor Globulus Hand Humidity Know Length Round Small Taking Through Timer Water
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
I make the proportion of one of these small Water-creatures to a Cheese-mite, to be like that of a Bee to a Horse:
ANTONIE VAN LEEUWENHOEK

Bee Cheese Creature Horse Make Mite One Proportion Small Water
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