Antonie van Leeuwenhoek: If any person examines by the microscope that...

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

Antonie van Leeuwenhoek

accomplished busy men

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

paper discovery people

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

taken joy believe

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. 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. This particle I concluded to be the heart.

Antonie van Leeuwenhoek

saws body heart

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

Antonie van Leeuwenhoek

rain water years

[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. 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

hard-work wisdom knowledge

Passing just lately over this lake, ... and examining this water next day, I found floating therein divers earthy particles, and some green streaks, spirally wound serpent-wise, and orderly arranged, after the manner of the copper or tin worms, which distillers use to cool their liquors as they distil over. 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

wise hair science

I have divers times examined the same matter (human semen) from a healthy man... not from a sick man... nor spoiled by keeping... for a long time and not liquefied after the lapse of some time... but immediately after ejaculation before six beats of the pulse had intervened; and I have seen so great a number of living animalcules... in it, that sometimes more than a thousand were moving about in an amount of material the size of a grain of sand... 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

men science moving

Examining this water...I found floating therein divers earthy particles, and some green streaks, spirally wound serpent-wise...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

wise water science

The 31th of May, I perceived in the same water more of those Animals, as also some that were somewhat bigger. 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) 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: 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

horse eye moving

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

science hands blood

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, ten hundred thousand of them could not equal the dimensions of a grain of such course Sand. There was discover'd by me a fifth sort, which had near the thickness of the former, but they were almost twice as long.

Antonie van Leeuwenhoek

eye science long

A man has always to be busy with his thoughts if anything is to be accomplished.

Antonie van Leeuwenhoek

thoughts man always busy

When I have supped too heavily of an evening, I drink in the morning a large number of cups of coffee, and that as hot as I can drink it, so that the sweat breaks out on me, and if by so doing I can't restore my body, a whole apothecary's shop couldn't do much, and that is the only thing I have done for years when I have felt a fever.

Antonie van Leeuwenhoek

me evening coffee morning

How inscrutable and incomprehensible are the hidden works of Nature!

Antonie van Leeuwenhoek

incomprehensible hidden how nature

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

hidden i-am will forever

I now found that the spider cannot fix its thread to anything without imprinting the hind part of its body on the place, by which pressure it emits an incredible number of excessively small threads diverging in every direction from whence we may conclude that as soon as the threads are exposed to the air, they lose their viscosity or gluey quality.

Antonie van Leeuwenhoek

lose place quality body

People who look for the first time through a microscope say, 'Now I see this, and then I see that,' and even a skilled observer can be fooled. On these observations I have spent more time than many will believe, but I have done them with joy, and I have taken no notice of those who have said, 'Why take so much trouble,' and, 'What good is it?'

Antonie van Leeuwenhoek

good look time people

Please bear in mind that my observations and thoughts are the outcome of my own unaided impulse and curiosity alone; for, besides myself, in our town there be no philosophers who practice this art, so pray, take not amiss my poor pen and the liberty I here take in setting down my random notions.

Antonie van Leeuwenhoek

thoughts alone myself art

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

without generation small impossible

If any person examines by the microscope that part towards the extremity of the spider's body from whence its thread proceeds, he will observe the spot to be, as it were, surrounded by five several protuberances or risings, each ending in a point and altogether forming a kind of enclosure.