I Cannot agree with you in the cause of that uncommon production you mention; my thoughts on this subject, and on some others connected with it, will appear by the following reflections.

Until the last hundred years or thereabout, it was supposed that in many instances life was produced by putrefaction, fermentation, &c. Leuwenhoek and other naturalists, clearly demonstrated that some animals which were supposed to owe their existence to the above causes, or in other words, to spontaneous generation, really had a regular production. This discovery established the general principle of omnia ab ovo—but it must be received with reserve and exception.

After giving every theory of the earth a patient reading, it seems to me probable that the whole world was originally covered with water to the depth of about three miles, which is about as much below the surface, as the highest mountains rise above it. This depth, though far below all soundings, bears no more proportion to the earth’s diameter, than that of the paper it is covered with does to a common globe. The idea of the sea approaching the center, and of course, possessing a superior share in quantity as well as surface of the earth, has occasioned many difficulties in accounting for the balance between the different sides of the globe; which vanish, if the sea is not supposed of a greater depth than necessity requires, or reason and probability warrant.

I consider all continents as a congeries of islands heaved up from the bottom of the sea at different times by vulcanos and earthquakes. Modern philosophers have discovered ancient vulcanos where they were never suspected to have existed, and the whole earth is full of evidence that it was once beneath the ocean. Marble, freestone, and many other substances abound in seashells and marine productions. It is frequently said that the sea has left many places which were once covered by it. Is it not rather to be supposed that those places have been elevated above the sea, than that the sea has sunk below them? There seems to be no cause in nature equal to the altering the quantity of water in the ocean, but we know that there are many causes equal to the elevating the land above it. If the sea had retired from the land, the retiring must have been equal in all places; this we are sure is not the case, therefore it is the land in that particular place that must be risen.

In the manner I suppose all land to have been first brought to light, many islands have been produced in our own time. What was under the water is forced above it. The marine substances on the surface by degrees decay; moss appears, grass succeeds, then the smaller kind of plants, bushes and trees. Animal life begins and goes on upon the same scale from the minuter, to beings of more consequence. This system is at least as general as the other, but like that must be received with many restrictions; for it is certain that by far the greater part of vegetables and animals would never be found self-produced in any one place, tho’ many might live, and indeed flourish, if brought there.

Let us proceed from reasoning to facts. Some voyager discovers an island evidently formed by a vulcano, and very remote from other countries; it is a perfect wood to the water’s edge, has some plants which exist no where but in that spot, together with others common to places in the same latitude. It is full of insects, reptiles, birds, and sometimes quadrupeds. Now, if every one of these organized bodies was not brought there, something must be self-produced.

In some islands of the East-Indies are serpents of an enormous size; who could carry them there? In all streams there are fish—how could they get there? Not from the sea, for fish which inhabit the source of rivers are as soon killed by salt water as in air, besides there are many rivers which do not run into the ocean. Perhaps this circumstance was never sufficiently considered. Every set of rivers is perfectly distinct from any other set. The greater number have some fish which exist no where but in the particular stream they are bred. Find any other cause for their first production than what must be taken from the old philosophy.

Let us attend to what we have always near us. Fill a vessel with water from the pump: it is pure, and contains neither animal, nor vegetable. After standing some days, a green substance begins to be formed in it, and which is inhabited by myriads of little beings: this seems the first step towards plants and animals. We are told indeed that the animalcules are from eggs laid by flies, and the green slime is a plant which has its proper seed. That the water may accidentally receive both eggs and seeds is highly probable; but these (by reasoning from other instances) seem the first efforts towards vegetable and animal life. Besides, it yet remains to be proved, that the air so abounds with flying seeds and insects. If the air swarmed, as is supposed, vision would be obstructed (as by a fog which consists of particles inconceivably small), and perhaps life in the nobler animals destroyed. The slime to be produced from seed then must have come from some of the same sort in the neighbourhood; besides, if its being produced in the water depended upon accident, which it does by this supposition, it must sometimes fail. Again, if the animals and vegetables, in the above instance, were from eggs floating in the air, why are the smallest always produced first? must it not sometimes happen that ova of a larger sort precede the smaller? which is never the case: not to mention the total impossibility of some ova, particularly of animals, being so conveyed.

It is well known that by pepper-water, and a variety of other mixtures, peculiar animalcules are produced. Can we suppose that the fly, which lays the egg from which this creature exists, continues floating in the air until some philosopher makes a mixture proper for its deposit? is it done often enough to preserve the species? What must the fly have done before pepper was brought from India? You may tell me that the egg was deposited there—well then, if the eggs are not hurt by the pepper being dried in an oven, happen to be brought to Europe, and fall in the way of a naturalist, the species is preserved. Much is not got by this. There is great reason for believing that the animalcule was really produced by the infusion, and did not exist before.

How are the worms in human bodies to be accounted for? There are some, it is true, which bear a resemblance to earth-worms, and are supposed to be eggs we take in with roots, vegetables, &c. Not to insist upon the impossibility of a creature intended to live in the cold earth existing on the hot stomach, it is well known that there are worms in the intestines which have no resemblance to any other thing in the creation—the jointed worm, for instance, which is found of many yards in length: indeed, if some accounts are to be credited, of some scores of yards. Where does this animal exist except in the stomach where it is found? Sheep, dogs, horses, &c. breed worms peculiar to themselves. I have seen frequently between the sound and back-bone of a whiting, long worms that were evidently bred there. As I have no system to support, I shall have no objection if you can account for these facts according to the present philosophy—but to me it seems absolutely impossible.

I may strengthen every thing I have advanced on self-production with additional arguments, and those from instances on the largest scale. The old and new continents are two immense islands. You will get little by supposing them once joined at Kamchatka. What should ever induce those animals which are never seen out of a hot climate, to travel so far North as the Strait between the continents? They do not approach it now, why should they then? Besides, has not each continent some creatures peculiar to itself? Did those in America come from countries where no such animals exist? If they did not, and are found in America only, what is the fair conclusion?

When an inhabitant of the old continent asks how America was peopled, why does the question stop there? How was it supplied with vegetables and animals? particularly river-fish; and whence came those creatures that exist no where else? Pray, what is to hinder an American from reversing the question? When did our people, he may say, first migrate and give inhabitants to the Eastern world? What answer can be given to these questions confident with the present system of philosophy?

There is something in the sound of self-production which seems like a contradiction. I mean nothing more by it, than that a vegetable or animal does in many instances first exist by a different principle than that upon which the species is afterwards continued. As the term does not exactly express this, it may easily be perverted from the sense in which I wish to be understood. Perhaps we shall find that self-production shocks the imagination more or less according to the size of the thing produced. Who would not sooner believe that cheese breeds mites, than that deserts produce elephants? And yet, according to our present philosophy, one is as possible as the other.

If the consequences I have drawn from these facts appear to you wrong, or the facts themselves ill-supported—convince me of my error, and the whole shall be retracted as freely as it is advanced by

Yours most faithfully, &c.