Why writers repeat thier ideas and refer their own works

Writers feel the love of thoughts and ideas and manifest their romance through the way they use the language or weave a story or a narrative.

It is inevitable that their love pops out often.

Only those who review or evaluate or criticize or analyze any writing mention as author reusing his/ her own aphorisms or repeating himself/ herself and so on.

It is not confined to a few authors. I have noticed this aphorisms in many authors because they ( aphorisms) convey authors' passion filled renewed romance with certain thoughts, opinions , ideas, reasons, emotions, reactions etc ( in some cases strong prejudices) which are internalized not as vague pr​e​mises or hypothesis but as some well grasped, deeply felt, clearly understood, conviction filled, fully crystalized concepts, ideologies, philosophies.

These are then ensconced in the safe soft corners of subconsciousness and may have some consistency.

They pop up often, even in pure fictions.

Incidentally, very often a writer prefers to refer to his/her own previous works or may automatically use similar or same expressions to convey specific ideas that will be made to be communicated through specific characters or topics.

Ideas, stories, the way language is used, the way a reader understands them are all interrelated and interconnected like the various parts of a fruit like kernel, nut, pulp and skin.

Which enhances ​the ​'what​s​' and ​the ​'how​s​' are subjective and this is the case even in epics and historical narratives. 

Which one compliments what and who knows it ? Is it the story of mahabharata or the 700 verses of bhawad geetha?

Stories are required for impact and thoughts and ideas for internalizing as reference manual.

Every product needs a good packing and every container becomes relevant and gets its value only based on its content.