thumb|300px|right|A traveller peers through an opening in the [[firmament in this illustration from Camille Flammarion's (Paris: Hachette, 1888), p. 163]]
The Flammarion engraving is a wood engraving by an unknown artist. Its first documented appearance is in the book ("The Atmosphere: Popular Meteorology"), published in 1888 by the French astronomer and writer Camille Flammarion. Several authors during the 20th century considered it to be either a Medieval or Renaissance artwork, but it is now seen as a 19th-century illustration of unknown authorship that imitates older artistic styles and themes. More recently, it has also been used as to represent a psychedelic experience.
Attribution
thumb|[[Hans Holbein the Younger, Ezekiel’s vision of God, the four living creatures, and a wheel within a wheel, published in Historiarum veteris instrumenti icones ad vivum expressae (1538)]]
In the early 20th century, the scholar Heinz Strauss dated the image to the period 1520–1530, while Heinrich Röttinger suggested that it had been made in 1530–60. The same image was used by psychoanalyst Carl Jung in his 1959 book Flying Saucers: A Modern Myth of Things Seen in the Skies. Jung speculated that the image was a Rosicrucian engraving from the 17th century. Weber argued that the work was a composite of images characteristic of different historical periods, and that it had been made with a burin, a tool used for wood engraving only since the late 18th century. the depiction of a spherical heavenly vault separating the Earth from an outer realm is similar to an illustration that begins the first chapter of Sebastian Münster's Cosmographia, first published in 1544, a book which Flammarion, an ardent bibliophile and book collector, might have owned.
The same paragraph had already appeared, without the accompanying engraving, in an earlier edition of the text published under the title of ("The Atmosphere: Description of the Great Phenomena of Nature", 1872). The correspondence between the text and the illustration is so close that one would appear to be based on the other. Had Flammarion known of the engraving in 1872, it seems unlikely that he would have left it out of that year's edition, which was already heavily illustrated. The more probable conclusion therefore is that Flammarion commissioned the engraving specifically to illustrate this particular text, though this has not been ascertained conclusively.
Possible literary sources
The idea of the contact of the Earth with a solid sky is one that repeatedly appears in Flammarion's earlier works. Commentators have suggested various literary passages that might have directly motivated the composition of the image in the Flammarion engraving. These included the Medieval legend of Saint Macarius the Roman, the Letters of François de La Mothe Le Vayer from the 17th century, and the classical argument for the infinitude of space attributed to Archytas of Tarentum (a friend of the philosopher Plato).
Legend of Saint Macarius
In his ("Imaginary Worlds and Real Worlds", 1864), Flammarion cites a legend of a Christian saint, Macarius the Roman, which he dates to the 6th century. This legend includes the story of three monks (Theophilus, Sergius, and Hyginus) who "wished to discover the point where the sky and the earth touch" (in Latin: ). After recounting the legend he remarks that "the preceding monks hoped to go to heaven without leaving the earth, to find 'the place where the sky and the earth touch,' and open the mysterious gateway which separates this world from the other. Such is the cosmographical notion of the universe; it is always the terrestrial valley crowned by the canopy of the heavens."
In the legend of St. Macarius, the monks do not in fact find the place where Earth and sky touch.
Letters of Le Vayer
In Flammarion recounts another story:
Flammarion also mentioned the same story, in nearly the same words, in his ("History of the Sky"):
The Letters referred to are a series of short essays by François de La Mothe Le Vayer. In letter 89, Le Vayer, after mentioning Strabo's scornful opinion of Pytheas's account of a region in the far north where land, sea, and air seemed to mingle in a single gelatinous substance, adds:
Le Vayer does not specify who this "anchorite" was, nor does he provide further details about the story or its sources. Le Vayer's comment was expanded upon by Pierre Estève in his Histoire generale et particuliere de l'astronomie ("General and Particular History of Astronomy", 1755), where he interprets Le Vayer's statement (without attribution) as a claim that Pytheas "had arrived at a corner of the sky, and was obliged to stoop down in order not to touch it."
The combination of the story of St. Macarius with Le Vayer's remarks seems to be due to Flammarion himself. It also appears in his Les terres du ciel ("The Lands of the Sky"):
Argument of Archytas
This historian of science Stefano Gattei has argued that the image in the engraving is directly inspired by an argument for the infinitude of space, due to the ancient Greek mathematician Archytas of Tarentum. Gattei quotes the version of this argument given in the commentary on Aristotle's Physics by Simplicius of Cilicia, written in the 6th century CE: