Sometimes the smallest words carry the largest assumptions.
Ask someone what time is doing.
The answer will often come without hesitation.
"It is passing."
The expression is so familiar that it scarcely sounds metaphorical at all.
Birthdays pass.
Weekends pass.
Years pass.
We speak of time passing almost as naturally as we speak of rain falling.
Yet familiarity should not exempt a concept from examination.
On the contrary, it may be the very reason to examine it.
Let us begin with an ordinary example.
A train passes a station.
What makes this statement true?
The train occupies different positions.
The station occupies a comparatively fixed position.
The train changes its relation to the station.
The word "passing" therefore describes a particular kind of change.
Something moves relative to something else.
Now consider a different sentence.
"Time passes."
What occupies different positions?
Relative to what?
Again, the question feels strangely awkward.
Not because it is obscure, but because we are unused to asking it.
The expression is so deeply woven into our language that it usually functions without scrutiny.
Perhaps we imagine ourselves standing still while time moves past us.
This picture is remarkably common.
We speak of "watching the years go by."
The future approaches.
The past recedes.
The present slips away.
Notice how naturally these expressions construct a scene.
There is an observer.
There is movement.
There is a direction.
There is something that moves.
The metaphor is extraordinarily vivid.
It is almost cinematic.
Yet another possibility presents itself.
Perhaps it is not time that moves.
Perhaps we move through time.
This expression is equally familiar.
We travel into the future.
We move towards tomorrow.
We leave yesterday behind.
Curiously, this second metaphor reverses the first.
In one, time moves while we remain still.
In the other, we move while time remains fixed.
Both cannot be literally true.
Yet we use them interchangeably with scarcely any sense of contradiction.
This is worth pausing over.
Imagine describing a railway journey in the same way.
Sometimes the train moves past the station.
Sometimes the station moves past the train.
One could adopt either description, provided one remained consistent.
But to alternate between them without noticing would quickly produce confusion.
With time, however, we do precisely this.
Sometimes time passes us.
Sometimes we pass through time.
Our language accommodates both pictures effortlessly.
The ease with which we shift between them may conceal the fact that they are different conceptual models.
One might object that these are merely figures of speech.
Indeed they are.
The question, however, is not whether they are metaphorical.
The question is whether different metaphors quietly commit us to different ways of imagining the phenomenon.
That possibility deserves attention.
There is another curiosity.
Passing usually presupposes persistence.
If a bird passes overhead, both the bird and the observer continue to exist throughout the event.
If time passes, what persists?
Does time itself continue while different portions of it move past us?
Do we remain stationary within it?
Or are we carried along with it?
The metaphor leaves these questions unanswered.
Yet they are precisely the questions that arise once the metaphor is taken seriously.
Perhaps the attraction of the metaphor lies elsewhere.
Perhaps "time passes" is simply a compact way of saying that the world changes.
Morning becomes afternoon.
Children become adults.
Leaves become soil.
Memories accumulate.
Nothing in this description requires time itself to be travelling anywhere.
What changes are the relations among events.
The metaphor of passing may simply gather these experiences into a familiar image.
If so, it has served us well.
But it has also done something more.
It has quietly transformed a description of changing experience into a description of time itself.
The transformation is subtle.
It is also profound.
There is an old philosophical habit of asking whether a word refers to a thing.
Sometimes the better question is different.
What kind of picture does the word encourage us to imagine?
"Passing" encourages movement.
It encourages direction.
It encourages persistence.
It encourages a traveller and a path.
Whether these ideas belong to time itself is another matter entirely.
None of this diminishes the beauty of the metaphor.
Quite the contrary.
Its beauty may explain its endurance.
It captures something deeply human.
We do experience loss.
Anticipation.
Memory.
Irreversibility.
The language of passing gives poetic form to these experiences.
That is no small achievement.
The difficulty begins only when poetry quietly becomes ontology.
Perhaps we should not ask whether time passes.
Perhaps we should first ask a simpler question.
What do we mean when we say that anything passes?
Only after answering that question can we know whether the metaphor has illuminated the phenomenon or merely lent it a familiar image.
The distinction is easy to overlook.
It may also be one of the most important distinctions we can make.