What is time? Our modern sense of time is homogenous. It divided and measured in "units" to be filled. Clock time. These time units have no meaning themselves. They are empty containers, filled with meaning by us, through activities we do within them.
This is how I think of time. Or rather, how I think of time, before I really think about it. It's likely that you think of time this way too. It's part of our social imaginary. Time is an asset to be managed through instrumental reason.
But this is not the only way to think about time, and it's a relatively new way of seeing time. Before the advent of precise time-keeping, dividing and engineering time in this way would have been hard to imagine.
In a A Secular Age, Charles Taylor identifies several types of time-consciousness that have been part of our social imaginary.
Modern "ordinary" time we already know.
A higher calendar time that inflects ordinary time with symbolic meaning. Liturgical time is an example. Anniversaries are another kind of higher time.
What did higher times do? One might say, they gathered, assembled, reordered, punctuated profane, ordinary time.
Time of origins
A time-before-time that sets the template for how society and ordinary time ought to be ordered. This is a time of legendary figures and mythical deeds.
The Garden of Eden, Noah's flood, the Exodus belong to a time of origins.
The Founding Fathers, The Declaration of Independence, the midnight ride of Paul Revere belong to a quasi-mythical time of origins in the US. This is why appeals to the Constitution have a religious tenor in some circles.
Platonic time is time-as-corruption. Platonic Forms are changeless. Time, decomposition and change hold sway in the sublunar, which has fallen short of the Forms. As you approach the heavens, time falls away, until you reach the unchanging realm of the Forms.
St Augustin developed a concept of time as potentiality. We gather from past experience to will into the future by acting in the present. For Augustin, God, who is pure potentiality, sits at the moment where all time is gathered, past and present, into an eternal now.
The unfathomable reaches of time we now grapple with, as our understanding of the universe unfolds. Time unmoored from any human refrence point. Billions and billions.
Deep Time is a new time-consciousness. It is awe-inspiring and disorienting. Many contemporary people consciously disavow it.
Deep Time caused the floor to drop out from the medieval cosmos picture. All of history used to fit within the stained glass story windows of a cathedral. Now we have... what? A dark abyss.
Nietze's Parable of the Madman captures the unmooring effect of this time-consciousness:
How could we drink up the sea? Who gave us the sponge to wipe away the entire horizon? What were we doing when we unchained this earth from its sun? Whither is it moving now? Whither are we moving? Away from all suns? Are we not plunging continually? Backward, sideward, forward, in all directions? Is there still any up or down? Are we not straying, as through an infinite nothing? Do we not feel the breath of empty space? Has it not become colder? Is not night continually closing in on us?