< it is obvious that you cannot distinguish the wholesome glass of water from the one that will give you typhoid, just as, without calling the telescope, >There is an obvious gap in the text here, both in the published version and the unpublished revised typescript. To quote the editors of the Collected Papers, ``since Russell's meaning is obvious, the missing lines have been reconstructed here.'' Following their lead, I have enclosed the inserted words in angle-brackets. [CRS]