The Stoics held with four basic categories, all viewed as bodies (substantial and insubstantial): (1) substance in the sense of substrate, primary formless matter; (2) quality, matters organization to differentiate and individualize something, and coming down to a physical ingredient such as pneuma, breath; (3) somehow holding (or disposed), as in a posture, state, shape, size, action, and (4) somehow holding (or disposed) toward something, as in relative location, familial relation, and so forth. Immanuel Kant expounded a table of judgments involving four three-way alternatives, in regard to (1) Quantity, (2) Quality, (3) Relation, (4) Modality, and, based thereupon, a table of four categories, named by the terms just listed, and each with three subcategories. Arthur Schopenhauers doctoral thesis was On the Fourfold Root of the Principle of Sufficient Reason. Franz Brentano held that any major philosophical period has four phases: (1) Creative and rapidly progressing with scientific interest and results; then declining through the remaining phases, (2) practical, (3) increasingly skeptical, and (4) literary, mystical, and scientifically worthless—until philosophy is renewed through a new periods first phase. (See Brentanos essay "The Four Phases of Philosophy and Its Current State" 1895, tr. by Mezei and Smith 1998.)
Four Evangelists – Matthew, Mark, Luke, and John
Four Doctors of Western Church – Saint Gregory the Great, Saint Ambrose, Saint Augustine, and Saint Jerome
Four Doctors of Eastern Church – Saint John Chrysostom, Saint Basil the Great, and Gregory of Nazianzus and Saint Athanasius
Four Galilean moons of Jupiter – Io, Europa, Ganymede, and Callisto
The Gang of Four was a Chinese communist political faction. The Fantastic Four: Mr. Fantastic, The Invisible Woman, The Human Torch, The Thing. The Teenage Mutant Ninja Turtles: Leonardo, Michelangelo, Donatello, Raphael
The Beatles were also known as the "Fab Four": John Lennon, Paul McCartney, George Harrison, Ringo Starr. Gang of Four is a British post-punk rock band formed in the late 1970s. Four rivers in the Garden of Eden (Genesis 2:10–14): Pishon (perhaps the Jaxartes or Syr Darya), Gihon (perhaps the Oxus or Amu Darya), Hiddekel (Tigris), and Prat (Euphrates). There are also four years in a single Olympiad (duration between the Olympic Games). Many major international sports competitions follow this cycle, among them the FIFA World Cup and its womens version, the FIBA World Championships for men and women, and the Rugby World Cup. There are four limbs on the human body. Four Houses of Hogwarts in the Harry Potter series: Gryffindor, Hufflepuff, Ravenclaw, Slytherin. Four known continents of the world in the A Song of Ice and Fire series: Westeros, Essos, Sothoryos, Ulthos. Each Grand Prix in Nintendos Mario Kart series is divided into four cups and each cup is divided into four courses.