In 1997, Stephen Jay Gould wrote an essay in Natural History that called for a truce between religion and science. "The net of science covers the empirical universe," he wrote. "The net of religion extends over questions of moral meaning and value." Gould was emphatic about keeping the domains separate, urging "respectful discourse" and "mutual humility." He called the demarcation "nonoverlapping magisteria" from the Latin magister, meaning "canon."
My Sunday School textbook informs us that
The "canon" of the scriptures comes from the Greek word kanon meaning "measuring rod" or "norm". (p. 76)
and, in the Glossary,
Magisterium - The teaching office of the Church. ... (p.230)
This latter term coming from the Latin magister, meaning "teacher". There might be circumstances where a teacher or schoolmaster would be referred to as a Canon, but Henig's use of it here obscures Gould's point.