What is time?

The impersonal time factor is the background of the material

manifestation as the instrument of the Supreme Lord. It is the ingredient

of assistance offered to material nature. No one knows where time began

and where it ends, and it is time only which can keep a record of the

creation, maintenance and destruction of the material manifestation. This

time factor is the material cause of creation and is therefore a self

expansion of the Personality of Godhead. Time is considered the

impersonal feature of the Lord.

Srimad Bhagavatam 3.10.11 purport