All 3 Uses

theme
in
Story of My Life
(Auto-generated)

My studies for the first year were English history, English literature, German, Latin, arithmetic, Latin composition and occasional themes.
Chpt 18 *

themes = essays written by a student
I write the exercises, daily themes, criticisms and hour-tests, the mid-year and final examinations, on my typewriter, so that the professors have no difficulty in finding out how little I know.
Chpt 20
A thousand odds and ends of knowledge come crashing about my head like hailstones, and when I try to escape them, theme-goblins and college nixies of all sorts pursue me, until I wish—oh, may I be forgiven the wicked wish!†
Chpt 20 *

Definitions:

(1) (theme as in: theme of the novel)
a basic idea that underlies what is being said or done -- especially in a literary or artistic work
(2) (theme as in: musical theme)
the initial or primary melody of a musical composition

or

(as in "theme song") music that is most repeated in a film, television series, or other theatrical production
(3) (theme as in: wrote a 2-page theme on my summer)
an essay written by a student

(This sense of theme is much rarer in recent decades than in the past.)
(4) (meaning too rare to warrant focus)