Two intertwining themes weave through the fabric of Timeline: the intricate tapestry of history and the relentless march of technology. Both subjects command significant attention within this narrative. The historians alongside Doniger regard the past as the bedrock upon which modern culture stands. Johnston eloquently likens those ignorant of history to "a leaf that didn't know it was part of a tree," emphasizing the alienation from one's roots without historical context.

Throughout the novel, Crichton underscores the necessity of historical knowledge: "Yet the truth was that the modern world was invented in the Middle Ages. Everything from the legal system, to nation-states, to reliance on technology, to the concept of romantic love had first been established in medieval times." Even Doniger, in his own way, acknowledges its significance. He anticipates a future where people will pay to immerse themselves in bygone eras, recognizing that individuals might prefer their idealized visions of history over stark realities. While the past may not always shimmer with allure or thrill, its profound significance resonates with every character.

The peril posed by technology weaves itself seamlessly into the fabric of contemporary literature, and Michael Crichton's Timeline is no exception to this thread. Crichton conjures a haunting image through the character of the cat, Wellsey, a hapless pioneer in the realm of nascent quantum travel experiments. The subtle yet sinister transcription errors from repeated journeys have led to the emergence of a "third eye, smaller and only partially formed." Beneath this unsettling eye lies a patch of flesh, culminating in a jarring piece of jaw that grotesquely juts out "like a tumor from the side of the face." This chilling invocation of the word 'tumor' stirs up visions of nuclear radiation fallout and the sinister specter of chemical contamination—echoes of the perils etched into our modern technological landscape. Crichton issues a stark warning: the advent of new technologies harbors the potential for similarly insidious, initially imperceptible effects.