You were kind enough to insert in your 210th number, of the 29th of July last, the memoir on the dynasty of the Assassins, and on the origin of their name; which I read at the public sitting of the Institute, on the 7th of the same month. That memoir has occasioned a letter, dated from Marseilles, the 16th of September, 1809, and signed “M. R., Old Residents in the Levant;” to be likewise inserted in your 269th number, of the 26th of September. I do not know whether I am mistaken in suspecting, that the signature of that letter disguises a justly celebrated name, whose authority might have added great weight to the objections contained in the letter, had the writer of it been inclined to make himself known. However, as the author, or authors, of that letter, in attacking (although in the most gentlemanly manner, and with the most obliging expressions) the etymology of the word _Assassins_, which I have proposed, display no common knowledge of the Arabic language, I think it becomes me to justify my opinion, and reply to their objections; the more so, as the paper which I read at the public sitting of the 1st of July, was but a very brief extract from a much more extended memoir; and that this memoir, as well as all the others that I have submitted to the judgment of the Ancient History and Literature Class of the Institute, will, perhaps, not be published during my life-time, owing to the caprice of circumstances, which neither I myself, nor that class of the Institute, have power to control. The origin which I attributed to the word _Assassin_, appears, to the authors of the letter in question, to be _too far fetched_; consequently, they propose another; and affirm, that the name of the Assassins is nothing more than the plural of _Hassas_, “a word which,” they add, “is employed by the people of Syria, and even of Lower Egypt, to designate _a thief of the night—a robber_.” These gentlemen might have supported their opinion by most respectable authorities; for their etymology is not new; and I did not fail to make mention of it, as well as of a host of others, which were, perhaps, unknown to them, in my memoir, read at the private sitting. This discussion was not admissible in a reading destined for a public meeting; I have, therefore, suppressed it entirely. Permit me to transcribe a few lines here:— “Thomas Hyde, I remarked, who had, no doubt, never encountered the true denomination of the _Assassins_, in any Arabic writer, believed, that it must be the Arabic word _Hassas_, derived from the root _Hassa_, which signifies, amongst other things, to _kill_, to _exterminate_. This opinion has been adopted by Menage and the learned Falconet. M. Volney has likewise admitted it, but without citing any authority.”