He spoke a sound word of warning that has gained a small deserved fame: “Don’t do that. If you ever got good you’d be mediocre.”
Second, from David Remnick’s profile Leonard Cohen Makes it Darker in the 17 October 2016 issue of The New Yorker:
In the early eighties, when he presented his record company with “Various Positions”—a magnificent album that included “Hallelujah,” “Dance Me to the End of Love,” and “If It Be Your Will”—Walter Yetnikoff, the head of CBS Records, argued with him about the mix.
“Look, Leonard,” he said, “we know you’re great, but we don’t know if you’re any good.”