what does "I can promise you the one but not the other " from Memoir of Sherlock Holmes (the final problem)

Question

What does this statement imply "I can promise the one but not the other " from the Memoirs of Sherlock Holmes ("The Final Problem"), at this link:

"'...It has been a duel between you and me, Mr. Holmes. You hope to place me in the dock. I tell you that I will never stand in the dock. You hope to beat me. I tell you that you will never beat me. If you are clever enough to bring destruction upon me, rest assured that I shall do as much to you.'

"'You have paid me several compliments, Mr. Moriarty,' said I. 'Let me pay you one in return when I say that if I were assured of the former eventuality I would, in the interests of the public, cheerfully accept the latter.'

"'I can promise you the one, but not the other,' he snarled, and so turned his rounded back upon me, and went peering and blinking out of the room.

This got me thinking who or what could be the "one" and the "other" it's frustrating that even now I haven't been able to figure it out. Guys your aid is sought on this .

Answer 1

'If you are clever enough to bring destruction upon me, rest assured that I shall do as much to you.' – Moriarty

This sets up the two things that we are are talking about: 1. is "Holmes destroying Moriarty" and 2. is "Moriarty destroying Holmes".

"'You have paid me several compliments, Mr. Moriarty,' said I. 'Let me pay you one in return when I say that if I were assured of the former eventuality I would, in the interests of the public, cheerfully accept the latter.' - Holmes

Holmes is saying here that if he were sure that he could destroy Moriarty (1.), he would be OK with Moriarty destroying him in return (2.). This is fairly unambiguous because Holmes uses the words "the former" and "the latter".

"'I can promise you the one, but not the other,' he snarled, and so turned his rounded back upon me, and went peering and blinking out of the room.

Here Moriarty is saying that he "can promise" to destroy Holmes (2.), but he cannot promise to allow himself to be destroyed by Holmes.

In general, when someone talks about "the one and not the other", you need to use context to determine which one it is. Moriarty obviously wants to survive, so he would not be willing to promise his own destruction (1.). So we can infer that he is saying that he "can promise" to destroy Holmes. Of course, a promise of "the one, but not the other" like this would not be acceptable to Holmes. But Moriarty is not making a real offer: he just wants to threaten Holmes.

Answer 2

more in context: sherlock holmes

'You have paid me several compliments, Mr. Moriarty,' said I. 'Let me pay you one in return when I say that if I were assured of the former eventuality I would, in the interests of the public, cheerfully accept the latter.''I can promise you the one, but not the other,' he snarled, and so turned his rounded back upon me, and went peering and blinking out of the room.

I (can) promise you idiom TFD

I can guarantee with total confidence (that something is the case)

As in :

I can promise you X ... but not Y.

Answer 3

Moriarty can promise Holmes that Holmes will be destroyed, but he 'cannot promise'(1) Holmes that Holmes will accept Holmes' destruction cheerfully;

(1) 'cannot promise X' is actually a poorly veiled threat. 'i cannot promise you X' here means 'i am very certain X will not happen'

i.e. a very convoluted way for Moriarty to say: 'Mr. Holmes, you will be completely destroyed, in a way that may not allow you to accept that destruction cheerfully, meaning with unbearable pain to you and your friends.' ---- Moriarty is basically reminding Holmes that whatever Holmes imagined to be the blowback from further interfering with Moriarty, Moriarty will come up with something so cruel that Holmes will rue the interference.