Sonnet CXX (120)

That you were once unkind, befriends me now, 

And for that sorrow, which I then did feel

Needs must I under my transgression bow,

Unless my nerves were brass or hammered steel.

For if you were by my unkindness shaken,

As I by yours, y' have pass'd a hell of time, 

And I, a tyrant, have no leisure taken

To weigh how once I suffer'd in your crime.

O, that our night of woe might have remember'd

My deepest sense, how hard true sorrow hits,

And soon to you, as you to me, then tendered

The humble salve which wounded bosoms fits!

   But that your trespass now becomes a fee;

   Mine ransoms yours, and yours must ransom me. 

3. Thinking that I have now inflicted on you similar pain. 

4. Unless my nerves, &c. Unless I were destitute of feeling. 

6. Y' have pass'd a hell of time. Cf. "Though waiting so be hell" (LVIII. 13); and Lucrece, 1287 and 1288:

"And that deep torture may be call'd a Hell,
When more is felt than one hath power to tell."

7, 8. And I a tyrant, &c. I, like a tyrant, have been regardless of the pain I inflicted, not even sparing time to think of the suffering I once endured. 

9, 10. Our night of woe. On that former occasion. The expression "night of woe" may be metaphorical, though it is, of course, possible that reference may be made to some particular night. Might have remembered my deepest sense. Might have caused my deepest sense to remember. 
11. And that I had soon tendered to you, as you tendered to me on that former occasion. 

12. The humble salve. The humble apology. Fits. Suits. 

13. That former trespass of yours against me has become something which I can offer as a payment and ransom for my own offence.