existence only matters as much as we make it matter, for if we did not think it mattered, it would never matter.

paraphrased:
nothing that ever has happened, ever could happen, and ever will happen has any meaning more than we mentally and emotionally assign it.

the genocide of the jews is of no more consequence than blowing one's nose; apart from the meaning(s) we assign these events, as we, as humans, have no control or power over true meaning. our emotions drive the purpose of the universe in our "own little worlds".