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Newton's Dark Secrets

Classroom Activity


Activity Summary
Students will read and interpret a passage from a famous alchemical text titled The Twelve Keys of Basil Valentine.

Learning Objectives
Students will be able to:

  • identify Sir Isaac Newton as a scientist and mathematician who practiced alchemy.

  • explain that alchemy is a medieval chemical philosophy.

  • interpret symbols and metaphors that describe different materials and procedures in an alchemical text.

  • practice using symbols and metaphors to conceal work as alchemists did.

Materials for each team
  • copy of the "Secret Symbols" student handout (PDF or HTML)
  • copy of the "The Keys to the Stone" student handout (PDF or HTML)
  • highlighting pen

Materials for Teacher Demonstration

  • copper sulfate
  • water
  • ungalvanized steel nail

Alchemy was a form of early modern chemistry. Alchemists sought to create the so-called philosophers' stone in order to, among other goals, change metals such as lead into gold. For Newton and other practicing alchemists of the 17th century, there was a philosophical and spiritual aspect of their work that involved transforming the chaos of our everyday world into a pure enlightened state. This journey to enlightenment is known as the Great Work.

Alchemists heavily coded their work in symbols and metaphors to both prevent backlash from the church and to keep the uninitiated from penetrating their secrets. Animals, humans, plants, colors, and celestial bodies were used to indicate different substances, processes, and the desired result of those processes. While there were no fixed rules in the use of symbolism (different symbols were often used to represent the same thing), there are a few common themes. Seven base elements—gold, silver, iron, mercury, tin, copper, and lead —for example, were associated with particular planets and zodiac signs. The products of chemical processes were represented by colors. Kings and queens represent gold and silver, respectively.

In this activity, students will read and interpret a medieval alchemical passage.

Key Terms

alchemy: A medieval chemical philosophy that aimed to change base metals to gold, discover a universal remedy for illness, and prepare an elixir that would enable one to live forever.

antimony: a metallic element with four allotropic forms; used in a wide variety of alloys.

elements: The seven base metals plus arsenic and sulfur. They were not elements in the modern sense.

philosophers' stone: A mythical substance believed to cure disease, confer immortality, and turn ordinary metals like lead into gold.

symbol: A printed or written sign for the purpose of representing an operation or action, an element, a quantity, a quality, or a relation (as in music).

symbolism: The practice of representing things using symbols or attributing symbolic meaning(s) to objects, events, or relationships.

  1. Have students name some universal symbols they commonly see. (Some symbols include graphic road signs, warning signs, or musical notes.). Ask students to name some symbol systems that do not use words. (Some examples include hieroglyphics, Braille, Zip codes, bar codes, or ISBN numbers.) Discuss with students why symbols are used. (Some reasons include to communicate without language, to encourage secrecy, or to efficiently communicate information.) Explain that alchemists used symbols and metaphors to describe different materials and procedures in alchemical texts and art.

  2. Alchemists believed in the transmutation of metals. One chemical reaction they used to support their claims was the change that occurred when iron came in contact with copper sulfate pools found near mines. Since there was no way to weigh the copper in the pools, it looked to many as though the naturally occurring copper sulfate was transmuting the iron into copper. You can demonstrate this reaction to students. Make a solution of copper sulfate and water. (The concentration is not important, but the solution should have a bright blue color, like that of the dry copper sulfate.) Dip an ungalvanized steel nail in the solution and let it stay there for about a minute. When you remove it, the nail will be plated with copper. (Point out to students that weighing the initial and final products would have shown that the iron did not transmute into copper.)

  3. Organize students into teams. Provide copies of the student handouts and highlighting pens to each team. Review The Twelve Keys of Basil Valentine and the "Keys to the Stone" with students.

  4. Have teams read the passage and then use the description of the common alchemical symbols to create their own interpretation of the text.

  5. When teams have finished interpreting the passage, discuss their results. How similar was each team's interpretation? What might account for any differences in interpretations? Why might teams—who worked from the same passage and key code—end up with different interpretations?

  6. As an extension, have students view the complete passage and/or additional passages of the Twelve Keys of Basil Valentine online at

Activity Answer

In the excerpted passage:

  • grey wolf is stibnite, an ore of antimony
  • Mars is iron
  • Saturn is lead
  • the king is gold

Students' answers should reflect that the passage describes the preparation of gold by mixing impure gold with stibnite and then heating the mixture in a hot fire three times to purify the gold. Other interpretations of the passage may include that the stibnite is derived from lead [the offspring of ancient Saturn], that stibnite is added to impure gold [cast to him the body of the king], that after being heated three times there is no stibnite left [when this has been performed thrice the Lion has overcome the wolf and will find nothing more to devour in him], and that at the end of the experiment, the king—or the gold—has been prepared [our Body has been rendered fit for the first stage of our work].

Find an actual page from one of Newton's 300-year-old alchemical notebooks, with parts decoded, at

Student Handout Questions

  1. Compare your team's interpretation of the text to others in the class. Did different teams come up with the same answer? Why or why not? Discuss and defend your choices. While students should all be able to identify the basic materials and procedure outlined in the text passage, the exact interpretation will vary among students based on their understanding of the procedure and context of the text. In addition, interpretations will vary due to the fact that different students will identify different sections and phrases of the passage as more important and/or having more relevance than others.

  2. Newton used his own symbols and phrases to describe the steps he took when performing alchemical experiments. Explain why he might have done this. Newton might have done this because he was obsessed with the idea of keeping his work a secret both from the society at large and from other alchemists.

Links and Books

Web Sites

NOVA—Newton's Dark Secrets
Discover more about who Sir Isaac Newton really was, find out what inspired the Principia, read what Einstein wrote about his predecessor, see one of Newton's 300-year-old manuscripts decoded, and learn about seven of Newton's greatest accomplishments.

Alchemy Web and Virtual Library
Offers comprehensive library of imagery, symbols, music, alchemical texts, and commentary.

Newton's Alchemy, Recreated
Describes a project to decipher Newton's chemical laboratory notebooks and manuscripts.

The Newton Project
Provides digital facsimile images of Newton's papers alongside text-encoded transcriptions on a split screen.


A Dictionary of Alchemical Imagery
by Lyndy Abraham. Cambridge University Press, 2001.
Documents alchemical symbolism from the early centuries AD to the late-20th century.

Alchemy Tried in the Fire: Starkey, Boyle, and the Fate of Helmontian Chymistry
by William R. Newman and Lawrence M. Principe. University of Chicago Press, 2002.
Examines the goals and practices of mid-17th century alchemists and prominent scientists and how their work contributed to the development of modern chemistry.


The "Secret Symbols" activity aligns with the following National Science Education Standards (see

Grades 5-8
Science Standard G

History and Nature of Science
History of science

Grades 9-12
Science Standard G

History and Nature of Science
Historical perspectives

Classroom Activity Author

Margy Kuntz has written and edited educational materials for 20 years. She has authored numerous educational supplements, basal text materials, and trade books in science, math, and computers.

Teacher's Guide
Newton's Dark Secrets

Video is not required for this activity
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