Is time a line?

A short question on the nature on time.

Is time a line?
Tick tock tick tock…
Second to second,
Minute to minute,
Day to day.

Are we stuck on this train?
Our origin the past,
Our destination the future,
Express line,
No stops,
Straight ahead.

Or is time fluid?
Moments connected
To moments,
One flowing into another,
Mixing and mingling,
Weaving and intertwining,
Forming what we see
As our life.