Does staring at the sun cause significant, permanent harm?

Of course, I think I can safely assume if an eye is left pointing directly towards sun for a long period of time it does get major damage. However, staring at the sun also hurts very quickly. That pain seems like a very natural^* defense mechanism against eye damage.

Also, I guess technically even a very quick glance at the sun does cause temporary eye damage, as there is a visible distortion spot in sight for a short while afterwards.

So the question is: Is possible for someone to naturally stare at the sun for an amount of time required for significant permanent eye damage, or whether the pain will become too much significantly sooner than any such damage would happen?

Then: If not, is it possible with simple willpower, without special training or medication, to force oneself to ignore the pain for a long enough time to cause such damage?

Also: Is there a difference in this between adults, children and babies?

And as a bonus, are there any special environmental situations where this does not apply? For example: sunset, sunrise, solar eclipse, major fog, underwater, or light filtered through something else.

^{* - Natural is here not in the sense of "everything natural is good", but in the sense of "it is reasonable to assume there would be an evolutive advantage from it".}