Philosopher’s stone (squared circle)
The philosopher’s stone was the substance alchemists sought for turning base metals into gold or silver. Its best-known emblem is the squared circle of Michael Maier: a circle inside a square, inside a triangle, inside a circle.
Meaning
The figure is Emblem 21 of Maier’s emblem book Atalanta fugiens, printed at Oppenheim by Johann Theodor de Bry (the Science History Institute’s copy is dated 1618). Its motto reads: “Make of the man and woman a circle, of that a quadrangle, of this a triangle, of the same a circle and you will have the stone of the Philosophers.” In the engraving a bearded man the historian Richard Oosterhoff identifies as Hermes Trismegistus holds a compass and points to the figure on a brick wall, a nude man and woman standing in its innermost circle. The stone was the alchemists’ goal, and, as the Science History Institute puts it, most early alchemical texts hid their knowledge behind drawings, symbols and metaphors.
Origin and history
Maier did not invent the figure. Oosterhoff traces it to the Rosarium philosophorum, the Rose Garden of the Philosophers, printed in 1550, where it closes the chapter on conception by the alchemical king and queen. What the stone itself was, writers explained differently. The 1911 Encyclopædia Britannica describes the medieval view that the stone or elixir was a principle drawn from sulphur, not ordinary sulphur, white for making silver and yellow or red for gold. In the seventeenth century, the Science History Institute’s Distillations magazine tells, an alchemist known as Dr Butler claimed to possess it, and an international network of scientists spent the 1650s and 1660s trying to learn whether he had found it. In Newton’s manuscripts the historian Lawrence Principe recognised notes on two of three “periods”, or steps, in making the stone, steps that Robert Boyle had described and that Newton and John Locke discussed in letters after Boyle’s death.
What the shapes stand for
Maier explains the figure in the discourse under the emblem, in its seventeenth-century English translation. The first circle is the simplest body, without angles. The square is the four elements. The triangle is body, spirit and soul, the same three as the tria prima, which show themselves in three colours before the work turns red: the body, or earth, in the blackness of Saturn; the spirit, as water, in a lunar whiteness; the soul, or air, in a solar citrine. The last circle is an “invariable redness”, in which “the woman is converted into the man, and made one with him”.
Squaring the circle
The emblem plays on an ancient problem of geometry. Maier writes that the squaring of the circle was not known to Plato himself, but that the natural philosophers knew a squaring of their own when they commanded a circle to be turned into a square and, by a triangle, back into a circle. His epigram ends: “If this too high and too abstruse you find, / Geometry will soon inform your mind.” Oosterhoff notes that the emblem spends most of its time on squaring the circle and little on the man and woman.
The stone and the serpent
In the three fifteenth-century miniatures at the Science History Institute, the transmutation from the formless first matter into the philosophers’ stone is anchored by the Ouroboros, the serpent swallowing its tail.
Read next
- Next in Occult and alchemical symbolsOuroborosA serpent curled into a circle with its tail in its mouth. The oldest known example is on a gilded shrine of Tutankhamun; Greek alchemists in Egypt later drew it around the words “the all is one”, and since the Renaissance it has usually been read as eternity.
- The same shape in Andean and Inca symbolsViracochaThe creator god of the Andes, who in the stories made the sun and moon at Lake Titicaca, called the peoples out of the land, and walked away into the sea. The Incas took him into their own pantheon, and an Inca emperor took his name.
See also
Tria prima: sulphur, mercury and salt, Pentagram, Baphomet, Planetary metals (☉ ☽ ☿ ♀ ♂ ♃ ♄).
Sources
- Emblema XXI, from Atalanta fugiens by Michael Maier, Johann Theodor de Bry, Oppenheim, 1618; Roy G. Neville Historical Chemical Library, Science History Institute Digital Collections, Emblema XXI
- Atalanta fugiens, Emblem 21: “Of the Secrets of Nature”, Michael Maier; 17th-century English translation in the digital edition, Furnace and Fugue (Brown University Digital Publications), Emblem 21: motto, epigram and discourse (English)
- Learned Failure and the Untutored Mind: Emblem 21 of Atalanta fugiens, Richard J. Oosterhoff, Furnace and Fugue (Brown University Digital Publications), Introduction
- Dr. Butler and the Quest for the Philosophers’ Stone, Distillations magazine, Science History Institute
- Chasing the Clues in Isaac Newton’s Manuscripts, Distillations magazine, Science History Institute, Boyle, Locke and the three “periods”
- Alchemy, Encyclopædia Britannica, 11th edition (1911), vol. 1, Wikisource, Mercury and sulphur
- Three Alchemical Miniatures, Cecilio M. Cooper, 13 March 2025, Science History Institute (Collections blog), “The Flower of Wisdom”
The same shape elsewhere
Browse symbols formed from circles, squares and rectangles or triangles.
Researched, edited and approved by Rory Hansen before publishing. Last reviewed October 10, 2026. How we research
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