A Real object may be External or Internal, i.e. mental, as a dream is. For only that is external whose possession of some character is [not merely] independent of individuals’ opinions, but whose possession of any such Real character is independent of any individuals’ thought about any subject and ideation of every kind.
From variant pages. The inserted words ('not merely') are from a rejected version of the sentence in question.
http://www.commens.org/dictionary/entry/quote-meaning-preface-9