Some might seem simple to encapsulate, but others could pose a challenge or at least surprise a layman.

From Merriam-Webster:

Essential Meaning of essence
1 : the basic nature of a thing : the quality or qualities that make a thing what it is
•   The essence of love is unselfishness.
•   The book’s illustrations capture the essence of the story.
•   Competition is the (very) essence of capitalism.

Topics: work, identity, employment, careers, calling, professions, vocations