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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

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

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

Accomplishment Busy Himself Man Thinking
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 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
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
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
I have oft-times been besought, by divers gentlemen, to set down on paper what I have beheld through my newly invented microscopia, but I have generally declined.
ANTONIE VAN LEEUWENHOEK

Decline Invention Myself Paper Time
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
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
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
And I imagine, that [ten hundred thousand] of these little Creatures do not equal an ordinary grain of Sand in bigness: And comparing them with a Cheese-mite (which may be seen to move with the naked eye)
ANTONIE VAN LEEUWENHOEK

Biggest Cheese Eye Grain Hundred Imagine Move Naked Ordinary Sand Thousand
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

Accomplish Always Anything Busy Men