Humans can often recognize the buried fragments of an only partially revealed cranium even when other bones may look like shards of stone. The human brain has a specific region for recognizing faces, and is so attuned to finding them that it can see faces in a few dots and lines or punctuation marks; the human brain cannot separate the image of the human skull from the familiar human face. Because of this, both the death and the now past life of the skull are symbolized.
Moreover, a human skull with its large eye sockets displays a degree of neoteny, which humans often find visually appealing—yet a skull is also obviously dead. As such, human skulls often have a greater visual appeal than the other bones of the human skeleton, and can fascinate even as they repel. Our present society predominantly associates skulls with death and evil. However, to some ancient societies it is believed to have had the opposite association, where objects like crystal skulls represent "life": the honoring of humanity in the flesh and the embodiment of consciousness.
The skull that is often engraved or carved on the head of early New England tombstones might be merely a symbol of mortality, but the skull is also often backed by an angelic pair of wings, lofting mortality beyond its own death.
Compare Hamlet's words "Here hung those lips that I have kissed I know not how oft" to Talmudic sources: "...Rabi Ishmael [the High Priest]... put [the severed head of a martyr] in his lap... and cried: oh sacred mouth!...who buried you in ashes...!". The skull was a symbol of melancholy for Shakespeare's contemporaries.
In Elizabethan England, The Death's-Head Skull, usually a depiction without the lower jawbone, was emblematic of bawds, rakes, Sexual Adventurers and prostitutes; The term Deaths-Head was actually parlance for these rakes, and most of them wore half-skull rings to advertise their station, either professionally or otherwise. The original Rings were wide silver objects, with a half-skull decoration not much wider than the rest of the band; This allowed it to be rotated around the finger to hide the skull in polite company, and to reposition it in the presence of likely conquests.
Venetian painters of the 16th century elaborated moral allegories for their patrons, and memento mori was a common theme. The theme carried by an inscription on a rustic tomb, "Et in Arcadia ego"—"I too [am] in Arcadia", if it is Death that is speaking—is made famous by two paintings by Nicholas Poussin, but the motto made its pictorial debut in Guercino's version, 1618-22 (in the Galleria Barberini, Rome): in it, two awestruck young shepherds come upon an inscribed plinth, in which the inscription ET IN ARCADIA EGO gains force from the prominent presence of a wormy skull in the foreground.
Next to the Magdalene's dressing-mirror, in a convention of Baroque painting the Skull has quite different connotations and reminds the viewer that the Magdalene has become a symbol for repentance. In C. Allan Gilbert's much-reproduced lithograph of a lovely Gibson Girl seated at her fashionable toilette, an observer can witness its transformation into an alternate image. A ghostly echo of the worldly Magdalene's repentance motif lurks behind this turn-of-the 20th century icon.
The skull becomes an icon itself when its painted representation becomes a substitute for the real thing. Simon Schama chronicled the ambivalence of the Dutch to their own worldly success during the Dutch Golden Age of the first half of the 17th century in The Embarrassment of Riches. The possibly frivolous and merely decorative nature of the still life genre was avoided by Pieter Claesz in his "Vanitas" (illustration, below right): Skull, opened case-watch, overturned emptied wineglasses, snuffed candle, book: "Lo, the wine of life runs out, the spirit is snuffed, oh Man, for all your learning, time yet runs on: Vanity!" The visual cues of the hurry and violence of life are contrasted with eternity in this somber, still and utterly silent painting.
The Serpent crawling through the eyes of a skull is a familiar image that survives in contemporary Goth subculture. The serpent is a chthonic god of knowledge and of immortality, because he sloughs off his skin. The serpent guards the Tree in the Greek Garden of the Hesperides and, later, a Tree in the Garden of Eden. The serpent in the skull is always making its way through the socket that was the eye: knowledge persists beyond death, the emblem says, and the serpent has the secret.
- Noi eravamo quello che voi siete, e quello che noi siamo voi sarete.
- "We were what you are; and what we are, you will be."
In Vajrayana Buddhist iconography, skull symbolism is often used in depictions of wrathful deities and of dakinis.