In an 1997 essay "Non-Overlapping Magisteria" for Natural History magazine, and later in his book Rocks of Ages (1999), Gould put forward what he described as "a blessedly simple and entirely conventional resolution to... the supposed conflict between science and religion."

He draws the term magisterium from Pope Pius XII's encyclical, Humani Generis (1950), and defines it as "a domain where one form of teaching holds the appropriate tools for meaningful discourse and resolution", and describes the NOMA principle as "the magisterium of science covers the empirical realm: what the Universe is made of (fact) and why does it work in this way (theory).

The magisterium of religion extends over questions of ultimate meaning and moral value. These two magisteria do not overlap, nor do they encompass all inquiry (consider, for example, the magisterium of art and the meaning of beauty)."