In philosophy the horror vacui stands for a theory initially proposed by Aristotle stating that nature “fears” empty space. Therefore empty space would always be trying to suck in gas or liquids to avoid being empty. The theory was for a long time widely accepted and still supported by Galileo Galilei. His pupil Evangelista Torricelli stated in 1644 that the level of mercury in a closed tube was dependent on the pressure of surrounding air. In 1647 Blaise Pascal proved this notion in his famous vide dans le vide (“emptiness in emptiness”) experiment. The Magdeburg Hemispheres by Otto von Guericke were in 1650 further proof that Aristotle's theory was not correct (see more on this topic in history of thermodynamics). For a scholarly discussion Leviathan and the Airpump, by Shapin and Schaffer 1985, is particularly instructive in the 17th century debate between Hobbes, supporting the plenum, and Boyle's experimental demonstration of the vacuum.
In visual art, horror vacui (a fear of empty spaces, also known as cenophobia) is the filling of the entire surface of an artwork with ornamental details, figures, shapes, lines and anything else the artist might envision. It may be considered the opposite of minimalism. Many examples of horror vacui in art come from, or are influenced by, the mentally unstable and inmates of psychiatric hospitals, and fall under the category of Outsider Art. The term is associated with the Italian critic and scholar Mario Praz, who used it to describe the suffocating atmosphere and clutter of interior design in the Victorian age. Older examples can be seen on Migration period art objects such as the jewellery at Sutton Hoo or the Ruthwell Cross. Moving east, this feeling of meticulously filling empty spaces permeates Arabesque Islamic art from ancient times to the present. Yet another example comes from ancient Greece during the Geometric Age (1100 - 900 BCE), when horror vacui was considered a stylistic element of all art. The mature work of the French Renaissance engraver Jean Duvet consistently exhibits horror vacui.
Horror vacui may have also had an impact, consciously or unconsciously, on graphic design by artists like David Carson or Vaughan Oliver, and in the underground comix movement in the work of S. Clay Wilson, Robert Crumb, Robert Williams, and on later comic artists such as Mark Beyer. The paintings of Williams, Faris Badwan, Joe Coleman and Todd Schorr are further examples of horror vacui in the modern Lowbrow art movement.
The artwork in the Where's Waldo series of children's books is a commonly-known example of horror vacui.
The Tingatinga painting style of Dar es Salaam in Tanzania is a contemporary example of horror vacui. Other African artists such as Malangatana of Mozambique (Malangatana Ngwenya) also fill the canvas in this way.
It also refers to the problem some artists face when encountering a fresh canvas. Where to put the first line or brushstroke can be paralysing to some.
It may also be used in reference to the fear of the ancient Romans in stepping beyond their own boundaries.