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

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

Creature Discover Live Rain 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
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 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
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

Amount Grain Material More Move Sand Size Sometimes Thousand
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
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 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