This is a great interview with The Bad Plus. They talk about Jazz and finding your voice, but it’s this part on humility that stood out for me:

I prefer to think that it’s possible to always sort of double-check yourself and be like, “Is this really the right thing?” and be searching.  The classic jazz example is John Coltrane: consummate musician, but really never stopped searching. I don’t think he ever believed the hype about himself.  He could’ve been like, “Man, I got it, I’m great.”  But that’s not the feeling you get. Coltrane was incomparably great, but he was also just humbly trying to figure it out.

This should always be our attitude when we design as well. If we think that we’ve figured out how people use computers, or exactly how human psychology works, or that we can design the perfect, seamless experience – then we tend to start designing for ourselves at the expense of our users. Never stop searching.

See also: Humble Design.