What does Blake's "to the Queen" mean?

I think the first two lines - simply put mean that no mortal man can know what death feels like.....what the gates to heaven (or wherever we shall go) look like. That only the dead can see that goldan door..but that when we do die, and begin our everlasting life, we find that we have the key to that golden door- we can not only see it- but we can pass through it. The entrance to the Gate is accessable by both the rich and the poor. I think the second part of the poem is saying that Englands Queen has died....and he is saying that her death is wonderful- she will be able to enter through the golden gate.

I think that this poem is just a beautiful poem to a beloved Queen who has passed. Making death a wonderous thing....makes loosing such a person a bit easier.

It seems to be a dedication of his poetry to a real queen - often works were dedicated to powerful figures. (Might be worth looking up a biography)

But yes, these are the doors of heaven which no living eyes may see, to which the queen of heaven - presumably the Virgin Mary (?) has the keys.

He then compares her with what appears to be the actual queen - calling her the shepherdess of England's people - and seems to be saying that, through his visionary poetry, he has been able to bring the glories of heaven, normally hidden in life, and show them to her and to others.

I am also wondering if the real queen is getting a bit of a subtle rap over the knuckles for not behaving like the queen of heaven, whose "riches" and golden key are for rich and poor alike.