1. glass: mirror.   wear: wear away.

2. dial: sundial.

3. vacant leaves: blank pages.   thy mind's imprint: i.e., your thoughts, written in the book.

4. this learning: i.e., mental profit contemplating what was just described, the destructive power of time?

6. mouthed: all-devouring; gaping.   will give thee memory: will remind you.

7. dial's shady stealth: slow progress of shadow on the sundial.

9. what: whatever.

10. waste blanks: empty pages.

11. Those children nurs'd, deliver'd from thy brain: those children nurtured, born from thy brain. —The "children" are metaphors for reflections on time and death.

12. To take a new acquaintance of thy mind: i.e., allow you to understand yourself in a new way.

13. offices: —"Offices" are duties to be performed; thus a policeman is referred to as an "officer" because he performs the office of protecting the public. In this poem the person addressed is being urged to perform a duty to himself.

14. profit: benefit.