Top 37 Quotes & Sayings by Antonie van Leeuwenhoek

We will admit that, out of the mud or sand which is found on the seashore or the beds of our rivers, at low water, shellfish or testaceous animals come forth, but it does not from thence by any means follow that they are produced without any regular course of generation.

I must confess... I don't know any tongue but the Nether-Dutch.

Life lives on life - it is cruel, but it is God's will. And it is for our good, of course, because if there weren't little animals to eat up the young mussels, our canals would be choked by those shellfish, for each mother has more than a thousand young ones at a 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.

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.

How inscrutable and incomprehensible are the hidden works of Nature!

In treating of the oak, I have considered that the species of it growing in warm climates is superior to that which is produced in cold countries. But we must not imagine this to be the case with all woods; on the contrary, the fir timber grown in cold countries is superior to that produced in warm ones, where its growth is rapid.

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.

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.

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.

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.

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.

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?'

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.

I have lately examined water, in which beaten pepper was steeped, and found two sorts of animals for shape, and each of those sorts to contain greater and smaller kinds: the greater I supposed the elder, the less the younger.

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.

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.

If we now plainly perceive that the passage of the blood from the arteries into the veins of the tadpole is not performed in any other than those vessels, which are so minute as only to admit the passage of a single globule at a time, we may conclude that the same is performed in like manner in our own bodies and in those of other animals.

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.

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

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.

Man comes not from an egg but from an animalcule that is found in male sperm.

No one can pretend to say that a fish is ever killed by heat, for many kinds of fish, in the middle of summer, and in the burning heat of the sun, do either play, as it were, on the surface of the water, or hide themselves under the leaves, weeds, or other substances at the bottom.

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.

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.

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?

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.

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. The first time bacteria were observed.

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

[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.

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.

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.

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.

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

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.]

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.

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.