A letter from Sherlock Holms to his friend Watson:
My dear Watson [it said]: I write these few lines through the courtesy of Mr. Moriarty, who awaits my convenience for the final discussion of those questions which lie between us. He has been giving me a sketch of the methods by which he avoided the English police and kept himself informed of our movements. They certainly confirm the very high opinion which I had formed of his abilities. I am pleased to think that I shall be able to free society from any further effects of his presence, though I fear that it is at a cost which will give pain to my friends, and especially, my dear Watson, to you.
I have already explained to you, however, that my career had in any case reached its crisis, and that no possible conclusion to it could be more congenial to me than this. Indeed, if I may make a full confession to you, I was quite convinced that the letter from Meiringen was a hoax, and I allowed you to depart on that errand under the persuasion that some development of this sort would follow. Tell Inspector Patterson that the papers which he needs to convict the gang are in pigeonhole M., done up in a blue envelope and inscribed “Moriarty.” I made every disposition of my property before leaving England, and handed it to my brother Mycroft. Pray give my greetings to Mrs. Watson, and believe me to be, my dear fellow, — Very sincerely yours, Sherlock Holmes
Question: Now, Sherlock Holmes is writing this mail to his friend [Dr Watson] adhering to the principles/ 21st century etiquette of professional writing.