Theme

A broad idea, message, or lesson that is conveyed by a work. The message may be about life, society, or human nature. Themes often explore timeless and universal ideas and may be implied rather than stated explicitly. Along with plot, character, setting, and style, theme is considered one of the fundamental components of fiction.

Techniques
Various techniques may be used to express themes.

Leitwortstil
Leitwortstil is the purposeful repetition of words in a literary piece that usually expresses a motif or theme important to the story. This device dates back to the One Thousand and One Nights, also known as the Arabian Nights, which connects several tales together in a story cycle. The storytellers of the tales relied on this technique "to shape the constituent members of their story cycles into a coherent whole."

Thematic patterning
Thematic patterning is "the distribution of recurrent thematic concepts and moralistic motifs among the various incidents and frames of a story. Thematic patterning may be arranged so as to emphasize the unifying argument or salient idea which disparate events and disparate frames have in common". This technique also dates back to the One Thousand and One Nights.