Dream of / Dream about

[Unregistered]

Could you tell me what the difference between "Dream of" and "Dream about" is? When do we use "of" and "about"?

1. "What could it know of death?" - Wordsworth...
2. I've never heard of him...
Would there be a difference in these sentences if I used "about" instead of "of"?

[Tdol]

The difference is quantative:

I've heard of him = I know his name and maybe a few facts
I heard about the problem = I am reasonably informed

With 'dream', I use 'about' for nocturnal brain activity and 'dream of' as an alternative to 'think' or 'conceive' - I wouldn't dream of being rude to her.