The literary convention is that the use of square parentheses [ ] in a book’s text indicates text that was added by someone other than the author, in order to add clarity to the text. This is clearly not the case here.

The fact is that almost the same set of words appears in the text of The Herald of Coming Good . This proves that the words were written by Gurdjieff.

Perhaps Gurdjieff wants us to treat this “as if the sentence were written by someone else.”