black
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In it, that sometimes more than a thousand were moving about in an amount of material the size of a grain of sand…

Antonie van Leeuwenhoek

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

Creature Discover Live Rain Water
Man has always to be busy with his thoughts if anything is to be accomplished.
ANTONIE VAN LEEUWENHOEK

Accomplish Always Anything Busy Men
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
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’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 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
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
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
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
[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
My determination is not to remain stubbornly with my ideas, but I’ll leave them and go over to others as soon as I am shown plausible reasons which I can grasp.
ANTONIE VAN LEEUWENHOEK

Determination Ideas Leaving Myself Reason Stubborn
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
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