time is a flat circle

"There is nothing new under the sun."

From the HBO show True Detective, season 1:

Someone once told me, "Time is a flat circle." Everything we've ever done or will do, we're gonna do over and over and over again.

The idea of time as a loop, spiral or circle, rather than a straight line, is shared among many philosophers, historical cultures, artists and mystics.

This is not necessarily meant objectively or scientifically, but rather in the ways our individual minds and collective consciousness process reality. Hyperstition and Hauntology are two such ideas, as is the idea of a self-fulfilling prophecy, where the power of suggestion and the unavoidable influence of the past has a powerful and often repetitive impact on the future. According to indigenous Mexican musician Debit, ancient Mayan culture conceived of time as a spiral.

Other cultural references to repetition, spirals, or time as circular:

In Arrival (spoiler alert), language is used to alter human perception to create memories of future events.
In the myth of Oedipus, he was warned he would kill his father and marry his mother, and ends up doing just that by trying to escape it.
Much of William Basinski's music is built of looped tape recordings that are played on repeat and very slowly break down over time.
Visual representations of the Fibonacci sequence in art and nature often manifest as spirals.
The infinitely climbing melody in the first six-minute movement of the song "Storm" by Godspeed You! Black Emperor.
The book Gödel, Escher, Bach (which is way too long, in my opinion) leans heavily on themes of self-reference, recursion, quines, etc. and introduces the idea of a "strange loop," which Hofstadter continued to write about in later work.