Time is the witness of the process of change.
The interesting is time seems to only be reminiscing, and the moment becomes the past immediately.
It's like the sum of every moment. Whenever you are, you tend to be limited your thoughts. It does not refer to the difference between today and yesterday, but being in it, things will slowly change and do not know.
To grasp the present, it is best to figure out what you are doing now!