Celebrating 24 Years on the Web
Find science on or your birthday

Today in Science History - Quickie Quiz
Who said: “I seem to have been only like a boy playing on the seashore, ... finding a smoother pebble or a prettier shell ... whilst the great ocean of truth lay all undiscovered before me.”
more quiz questions >>
Thumbnail of Thomas Jefferson (source)
Thomas Jefferson
(13 Apr 1743 - 4 Jul 1826)

American statesman, astronomer, scholar and inventor who wrote the Declaration of Independence (1776) and organized the Lewis and Clark expedition (1803). His only full-length book, Notes on the State of Virginia contains an outline of the geography, flora and fauna of Virginia, and established his reputation as a scholar and a pioneering American scientist.

Thomas Jefferson
“The plough ... is really like sorcery”

Illustrated Quote - Large (800 x 400 px)

“The plough is to the farmer what the wand is to the sorcerer. Its effect is really like sorcery.”
— Thomas Jefferson
In letter to Charles Willson Peale (1813).

More Thomas Jefferson quotes on science >>

A letter by Jefferson on soil erosion control
and water conservation

Charles Willson Peale (1741-1827), was in his time well-known for his talent as a portrait painter, and for founding the famous Peale’s Museum of Art and Natural History in Philadelphia. But through his life, Peale was a man of versatile talents, including naturalist, taxidermist, politician and silversmith. Peale also had great ingenuity and mechanical skill to make coaches, harnesses, clocks and watches. It is no surprise to find that Thomas Jefferson shared interests and exchanged numerous letters with him, on various subjects.

In a letter, dated 17 Apr 1813, Jefferson gave Peale guidance on how to plough his farmland for best results. In the text of the letter below, Jefferson described best practices in soil and water conservation. He was concerned to stop the use of ploughing methods with straight furrows, that resulted in top soil depletion as it washed off the surface of the fields and into the rivers. The remedy was to plough following horizontally around the contours of the land. The furrows then would also hold water for the benefit of the crops, instead of letting it rapidly run off down the hill.

Thus, the proper ploughing technique would give so much better crop yield, he compared it to sorcery, with the subject quote shown within this letter. Also notice Jefferson’s mathemical mind, as he wrote to Peale:

“Your position that a small farm well worked and well manned, will produce more than a larger one ill-tended, is undoubtedly true in a certain degree. There are extremes in this as in all other cases. The true medium may really be considered and stated as a mathematical problem:

‘Given the quantum of labor within our command, and land ad libitum offering it’s spontaneous contributions: required the proportion in which these two elements should be employed to produce a maximum.’

It is a difficult problem, varying probably in every country according to the relative value of land and labor. The spontaneous energies of the earth are a gift of nature, but they require the labor of man to direct their operation. And the question is so to husband his labor as to turn the greatest quantity of this useful action of the earth to his benefit. Ploughing deep, your recipe for killing weeds, is also the recipe for almost every thing good in fanning.

The plough is to the farmer what the wand is to the sorcerer. Its effect is really like sorcery.

In the country wherein I live we have discovered a new use for it, equal in value almost to it’s services before known. Our country is hilly and we have been in the habit of ploughing in strait rows whether up and down hill, in oblique lines, or however they lead; and our soil was all rapidly running into the rivers.

We now plough horizontally following the curvatures of the hills and hollows, on the dead level, however crooked the lines may be. Every furrow thus acts as a reservoir to receive and retain the waters, all of which go to the benefit of the growing plant, instead of running off into the streams. In a farm horizontally and deeply ploughed, scarcely an ounce of soil is now carried off from it. In point of beauty nothing can exceed that of the waving lines & rows winding along the face of the hills & vallies. The horses draw much easier on the dead level, and it is in fact a conversion of hilly grounds into a plain. The improvement of our soil from this cause the last half dozen years, strikes every one with wonder.


For this improvement we are indebted to my son-in-law, Mr. Randolph, the best farmer, I believe, in the United States, and who has taught us to make more than two blades of corn to grow where only one grew before. If your farm is hilly, let me beseech you to make a trial of this method. To direct the plough horizontally we take a rafter level1 of this form. A boy of 13 or 14 is able to work it round the hill, a still smaller one with a little hough2 marking the points traced by the feet of the level. The plough follows running thro’ these marks. The leveller having compleated one level line thro’ the field, moves with his level 30 or 40 yards up or down the hill, and runs another which is marked in like manner & traced by the plough, and having thus run what may be called guide furrows every 30 or 40 yards thro the field, the ploughman runs the furrows of the intervals parallel to these. In proportion, however, as the declivity of the hill varies in different parts of the line, the guide furrows will approach or recede from each other in different parts, and the parallel furrows will at length touch in one part, when far asunder in others, leaving unploughed gores between them. These gores we plough separately. They occasion short rows & turnings which are a little inconvenient, but not materially so.

I pray you to try this recipe for hilly grounds. You will say with me, ‘Probatum est,’3 and I shall have the happiness of being of some use to you, and thro’ your example to your neighbors, and of adding something solid to the assurances of my great esteem & respect.”


[1 To clarify the use of a “rafter level” an annotated diagram, not in the original text, is shown here. It is a simple A-frame made from light, but rigid, wooden struts (r, s) of suitable length, say 8 to 12 ft each, to form a span of 12 to 20 ft between each foot of the frame. The horizontal member (m, n) is securely fastened about half-way up the legs. A plumbline is attached from the apex. With the legs on known horizontal ground (A, B), a notch is made at the point of contact (e, e) of the string of the plumbline against the crosspiece. To use in the field, the frame is set with the rear foot, A, at the start of the first furrow. A helper, which can be a boy, digs a small hole there with a hoe. The frame can then be swivelled around until the other foot, B, rests on the ground ahead such that the plumbline is on the notch, indicating the two feet are horizontal to each other. Another hole is dug at B. The frame is advanced to find the next point level to the previous hole, and another hole is chopped in the dirt with the hoe. The process is repeated until the end of the furrow is reached. This leaves a series of markers from the piles of fresh dirt from each hole, which can be seen for many yards. The farmer can then guide his plough, following the course of the holes. The hoe is a convenient way to make markers instead of carrying a bundle of stakes or sticks that must be driven into the ground. This use of a rafter level to plough contoured furrows is described in a number of books for farmers through several decades in the nineteenth century.
2 Presumably “hoe.”
3 “It is proven.” —Webmaster.]

Larger diagram of a rafter level, not in original text, added from another source, as shown above. Introductory text by Webmaster, with quote from a single, long paragraph in the letter from Jefferson at Monticello to Charles Willson Peale (17 Apr 1813). A few paragraph breaks were added to help readability on the web page. The full text of the letter appears in The Jefferson Papers: 1770-1826 (1900), 179. (source)

See also:
  • Science Quotes by Thomas Jefferson.
  • 13 Apr - short biography, births, deaths and events on date of Jefferson's birth.
  • Jefferson As A Man Of Science - Preface to The Writings of Thomas Jefferson, Vol. 19.
  • Thomas Jefferson on Education and Science from a report on establishing the University of Virginia (1818).
  • Thomas Jefferson - context of quote “To indulge in the rich fields of nature” - Medium image (500 x 250 px)
  • Thomas Jefferson - context of quote “To indulge in the rich fields of nature” - Large image (800 x 400 px)
  • Thomas Jefferson - context of quote “The plough ... is really like sorcery” - Medium image (500 x 250 px)
  • Thomas Jefferson - context of quote “Chemistry … among the most useful of sciences” - Medium image (500 x 250 px)
  • Thomas Jefferson - context of quote “Chemistry … among the most useful of sciences” - Large image (800 x 400 px)
  • Thomas Jefferson - context of quote “The patient … sometimes gets well in spite of the medicine. ” - Medium image (500 x 250 px)
  • Thomas Jefferson - context of quote “The patient … sometimes gets well in spite of the medicine. ” - Large image (800 x 400 px)
  • Thomas Jefferson on Quack Medicine - from Letter to Dr. Caspar Wistar (1807)
  • Thomas Jefferson - context of quote “Nature intended me for the tranquil pursuits of science” - Medium image (500 x 250 px)
  • Thomas Jefferson - context of quote “Nature intended me for the tranquil pursuits of science” - Large image (800 x 400 px)
  • Thomas Jefferson - context of quote “The ocean ... like the air, is the common birthright of mankind” - Medium image (500 x 250 px)
  • Thomas Jefferson - context of quote “The ocean ... like the air, is the common birthright of mankind” - Large image (800 x 400 px)
  • Thomas Jefferson: Scientist, by Edwin Thomas Martin. - book suggestion.

Nature bears long with those who wrong her. She is patient under abuse. But when abuse has gone too far, when the time of reckoning finally comes, she is equally slow to be appeased and to turn away her wrath. (1882) -- Nathaniel Egleston, who was writing then about deforestation, but speaks equally well about the danger of climate change today.
Carl Sagan Thumbnail Carl Sagan: In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion. (1987) ...(more by Sagan)

Albert Einstein: I used to wonder how it comes about that the electron is negative. Negative-positive—these are perfectly symmetric in physics. There is no reason whatever to prefer one to the other. Then why is the electron negative? I thought about this for a long time and at last all I could think was “It won the fight!” ...(more by Einstein)

Richard Feynman: It is the facts that matter, not the proofs. Physics can progress without the proofs, but we can't go on without the facts ... if the facts are right, then the proofs are a matter of playing around with the algebra correctly. ...(more by Feynman)
Quotations by:Albert EinsteinIsaac NewtonLord KelvinCharles DarwinSrinivasa RamanujanCarl SaganFlorence NightingaleThomas EdisonAristotleMarie CurieBenjamin FranklinWinston ChurchillGalileo GalileiSigmund FreudRobert BunsenLouis PasteurTheodore RooseveltAbraham LincolnRonald ReaganLeonardo DaVinciMichio KakuKarl PopperJohann GoetheRobert OppenheimerCharles Kettering  ... (more people)

Quotations about:Atomic  BombBiologyChemistryDeforestationEngineeringAnatomyAstronomyBacteriaBiochemistryBotanyConservationDinosaurEnvironmentFractalGeneticsGeologyHistory of ScienceInventionJupiterKnowledgeLoveMathematicsMeasurementMedicineNatural ResourceOrganic ChemistryPhysicsPhysicianQuantum TheoryResearchScience and ArtTeacherTechnologyUniverseVolcanoVirusWind PowerWomen ScientistsX-RaysYouthZoology  ... (more topics)

Thank you for sharing.
- 100 -
Sophie Germain
Gertrude Elion
Ernest Rutherford
James Chadwick
Marcel Proust
William Harvey
Johann Goethe
John Keynes
Carl Gauss
Paul Feyerabend
- 90 -
Antoine Lavoisier
Lise Meitner
Charles Babbage
Ibn Khaldun
Ralph Emerson
Robert Bunsen
Frederick Banting
Andre Ampere
Winston Churchill
- 80 -
John Locke
Bronislaw Malinowski
Thomas Huxley
Alessandro Volta
Erwin Schrodinger
Wilhelm Roentgen
Louis Pasteur
Bertrand Russell
Jean Lamarck
- 70 -
Samuel Morse
John Wheeler
Nicolaus Copernicus
Robert Fulton
Pierre Laplace
Humphry Davy
Thomas Edison
Lord Kelvin
Theodore Roosevelt
Carolus Linnaeus
- 60 -
Francis Galton
Linus Pauling
Immanuel Kant
Martin Fischer
Robert Boyle
Karl Popper
Paul Dirac
James Watson
William Shakespeare
- 50 -
Stephen Hawking
Niels Bohr
Nikola Tesla
Rachel Carson
Max Planck
Henry Adams
Richard Dawkins
Werner Heisenberg
Alfred Wegener
John Dalton
- 40 -
Pierre Fermat
Edward Wilson
Johannes Kepler
Gustave Eiffel
Giordano Bruno
JJ Thomson
Thomas Kuhn
Leonardo DaVinci
David Hume
- 30 -
Andreas Vesalius
Rudolf Virchow
Richard Feynman
James Hutton
Alexander Fleming
Emile Durkheim
Benjamin Franklin
Robert Oppenheimer
Robert Hooke
Charles Kettering
- 20 -
Carl Sagan
James Maxwell
Marie Curie
Rene Descartes
Francis Crick
Michael Faraday
Srinivasa Ramanujan
Francis Bacon
Galileo Galilei
- 10 -
John Watson
Rosalind Franklin
Michio Kaku
Isaac Asimov
Charles Darwin
Sigmund Freud
Albert Einstein
Florence Nightingale
Isaac Newton

by Ian Ellis
who invites your feedback
Thank you for sharing.
Today in Science History
Sign up for Newsletter
with quiz, quotes and more.