Why is the poet sure that time will not affect his beloved?
Chapter- A slumber did my spirit seal

Dear student

The post is sure that time wouldn't affect his beloved because she is already dead. A dead thing is immortal and it is universally accepted fact that immortality is not affected by time or the physical world. She is beyond the action and reaction of all the five senses and earthly body. She has become  a part of nature's diurnal course.

I hope it helps you!

Regards