We perceive time in at least three different ways.
First is chronological. We measure time in scientifically regulated intervals, and demarcate events in our lives and on the calendar with counted numbers that label moments according to a clock. This is the most objective marker of time we have.
Second is with respect to other lifetimes. We talk about how people who came before us “live in the past” and how the younger generations are “living in the future.” We improve society “for future generations.” Time, in this sense, is a more subjective interval granted on a generational basis, and shared amongst the inhabitants of each zeitgeist.
Third is as a narrative, with perhaps a beginning, a middle, and an end. When we take a moment of introspection and tell stories about our past, we don’t tell stories with perfect respect to the clock, but instead tell it as if we’re describing a painting. We omit the weeks and months that don’t matter and linger on the seconds that make the days. We may choose to provide an overview before diving into the details. We build ourselves narratives about whole chunks of time that we’ve lived through as single, unbroken units of experience, even though they’re in fact collections of smaller moments. This is the most subjective of the ways we remember time: as a collection of stories, an anthology of personal narratives bound only loosely by the monotonic hands of the clock.
A full elaboration of this idea ended up on my blog, as How we measure time