It lacks elegance. But I suppose it will sound more natural coming from you. Very well.
[. . .]
You must swear, then, by something of meaning to you that you will never invoke this phrase for any reason but to inform me that I am not in possession of all my faculties or have in some other way been compromised. And you must swear that you will never share this phrase with any other soul.
no subject
It lacks elegance. But I suppose it will sound more natural coming from you. Very well.
[. . .]
You must swear, then, by something of meaning to you that you will never invoke this phrase for any reason but to inform me that I am not in possession of all my faculties or have in some other way been compromised. And you must swear that you will never share this phrase with any other soul.