In the "hollow crown" speech in Richard II, there is a line with the words "Cover your heads". I need a paraphrase for this line. What does Shakespeare imply by this line in the context of this speech?
The words occur in a monologue by Richard II (Act III, scene 2) which contains the following lines (emphasis mine):
for within the hollow crown
That rounds the mortal temples of a king
Keeps Death his court and there the antic sits,
Scoffing his state and grinning at his pomp,
Allowing him a breath, a little scene,
To monarchize, be fear'd and kill with looks,
Infusing him with self and vain conceit,
As if this flesh which walls about our life,
Were brass impregnable, and humour'd thus
Comes at the last and with a little pin
Bores through his castle wall, and farewell king!
Cover your heads and mock not flesh and blood
With solemn reverence:
The main idea in these lines is that kings may be allowed for a while to "monarchize, be fear'd and kill with looks" (i.e. order somebody's execution with a glance), their bodies are not as impregnable as castle walls, so they die just as easily as other human beings.
In the last two lines, "solemn reverence" is what a king usually expects; while the king remains covered, the courtiers around him take off their hats. Wearing a hat in somebody else's presence implies equality, whereas the king is God's representative on earth, so he has not equal in his kingdom. Earlier in the same scene, Richard had said (my emphasis),
Not all the water in the rough rude sea
Can wash the balm off from an anointed king;
The breath of worldly men cannot depose
The deputy elected by the Lord:
The highlighted lines from the hollow-crown speech (first quote above) mark quite a change when compared with the earlier quote. Richard here says that kings are just human beings, i.e. "flesh and blood", and that treating ordinary human beings with "solemn reverence" constitutes a form of mockery. This is why the people around him should "cover [their] heads", i.e. put on their hats again as a mark of equality with him.
I believe it's a reference to "mourning dress," meaning that those mourning a death would cover themselves to indicate their grief. There's an interesting article here, which includes a painting of Richard II's funeral, by coincidence. Emphasis mine:
Similarities with nuns are clear; the rejection of a sexual lifestyle, dressing in black, grey and white to symbolize the loss of joy, while nuns would wear black, grey, brown and white to symbolise purity, humility and chastity. Sexual anonymity was present in both costumes, as well. Nuns would be be draped in fabric and hiding their faces, even to the point of shaving one’s head, rejected any interest in vanity. Similarly, widows were hidden under veils and drapery, wearing clothes that were out of fashion to represent their lack of interest in society.