Nelson Mandela's misinformed view of Gandhi don't change history any more than your hilarious denial of basic facts does.
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Janab ...... you are right you cannot change history and the place Gandhi has in history no one will be able to change. YOu are free to write whatever you want to write. I can hook you up to websites that cast doubts like this on even the "holy cows" like Jesus and the Prophet .... but that does not matter .... people know what they are and what they stand for ..... so does Gandhi .... he does not need a certificate from you.
If you get a chance to read "My experiments with Truth" ... he has discussed his own mistakes and follies and how he learnt from them.