The passage of time for the other seemed excessively slow.
This sculpture could be regarded as a carbon-based life form.
It's not that carbon-based life forms lack life, but rather the time scale of their life is too vast.
Just as if the sun were viewed as a life form, from birth to expansion and eventual extinction, it has tens of billions of years.
The span of a human life is only several decades.
If one stretched out the events of a human's life over tens of billions of years, how much time would each event occupy?
You would need many years just to eat breakfast.
Raising your hand would take many years as well.
But in your perception, you simply had a meal and raised a hand.
That is the time scale and temporal domain of carbon-based life forms.
Of course, this is just rambling, the actual integration with the Dao by immortals is much more complex and can't be explained so simply.