Shakespeare

In the poem "Shall I compare thee to a summer's day?"

What exactly is shakesphere saying in the phrase:

"Nor shall death brag thou wand'rest in his shade, when in eternal lines to time thou grow'st"

Sorry, I am Old english illiterate. Thanks for any help you can give.

Shakespeare wrote in early modern English.

The meaning isn't perfectly clear to me, either. It's somewhere in the neighborhood of "You're not getting older, you're getting better."