What is a hypernym for different fields of expertise? [duplicate]

It was only after he mastered psychology, philosophy, history, spiritualism, prophesizing and religion, in his old age, that he knew his know he could be at peace. He mastered all these ____ (collective word).

The best fit I can think of fields but could mean anything really and is too generic. Sciences sounds better since he researched it from a fundamental point of view but history, prophesizing and religion are not sciences. It's not in school or academic, and spiritualism is not a subject, so subjects doesn't sound correct. Is there a better word for fields that sounds more high-brow?

Solution 1:

To correct the spelling of Bitter dregs:

disciplines:

A branch of knowledge, typically one studied in higher education.

Solution 2:

How about specialties? From Lexido:

specialty: A pursuit, area of study, or skill to which someone has devoted much time and effort and in which they are expert.

Your example (edited):

It was only after he mastered the specialties of psychology, philosophy, history, spiritualism, prophesizing, and religion, in his old age, that he knew he could be at peace.

Another possibility that might work in your desired context is esoterica. From Lexico:

esoterica: Esoteric or highly specialized subjects or publications.

Your example (edited):

It was only after he mastered the esoterica of psychology, philosophy, history, spiritualism, prophesizing, and religion, in his old age, that he knew he could be at peace.