  This paper investigates the historical origin and ancestors of typicality,
which is now a central concept in Boltzmannian Statistical Mechanics and
Bohmian Mechanics. Although Ludwig Boltzmann did not use the word typicality,
its main idea, namely, that something happens almost always or is valid for
almost all cases, plays a crucial role for his explanation of how thermodynamic
systems approach equilibrium. At the beginning of the 20th century, the focus
on almost always or almost everywhere was fruitful for developing measure
theory and probability theory. It was apparently Hugh Everett III who first
mentioned typicality in physics in 1957 while searching for a justification of
the Born rule in his interpretation of quantum mechanics. The historically
closest concept before these developments is moral certainty, which was
invented by the medieval French theologian Jean Gerson, and it became a
standard concept at least until the Age of Enlightenment, when Jakob Bernoulli
proved the Law of Large numbers.
