Stalin reputedly said "I know that after my death a pile of rubbish will be heaped on my grave, but the wind of History will sooner or later sweep it away without mercy". What did he mean by this?
He never really said that, at least there's no authentic source for this quote.
The exact quote was originally published in two books, one was Felix Chuyev's book '140 conversations with Molotov' where Molotov supposedly quotes Stalin and the other was marhsal Golovanov's memoirs where it is claimed he met with Stalin on the 6th of December, 1943, and heard the same saying. The problem is that the second book was also edited for publishing by Chuyev. That makes it hard to consider the quote authentic.
A similar saying of Stalin was reportedly quoted by Alexandra Kolontai in her personal diary, it was attributed to her by historian Mikhail Trush in a 1998 magazine issue. In that story Kolontai tells that she met Stalin at the Kremlin in November, 1939, and had a personal conversation with him. The problem is that in 2001 the diaries of Kolontai were published and they had no such quote and also showed that she didn't meet Stalin in November, 1939, and so shows the journal of Stalin's meetings with visitors.