Harlan Ellison said this quote

I know that pain is the most important thing in the universes. Greater than survival, greater than love, greater even than the beauty it brings about. For without pain, there can be no pleasure. Without sadness, there can be no happiness. Without misery there can be no beauty. And without these, life is endless, hopeless, doomed and damned. Adult. You have become adult.

~ Harlan Ellison

The two most common elements in the universe are Hydrogen and stupidity.

~ Harlan Ellison

It is not merely enough to love literature if one wishes to spend one's life as a writer. It is a dangerous undertaking on the most primitive level. For, it seems to me, the act of writing with serious intent involves enormous personal risk. It entails the ongoing courage for self-discovery. It means one will walk forever on the tightrope, with each new step presenting the possiblity of learning a truth about oneself that is too terrible to bear.

~ Harlan Ellison

When you're all alone out there, on the end of the typewriter, with each new story a new appraisal by the world of whether you can still get it up or not, arrogance and self-esteem and deep breathing are all you have. It often looks like egomania. I assure you it's the bold coverup of the absolutely terrified.

~ Harlan Ellison