In Renaissance literature, the sun is a common symbol of royalty, and Shakespeare uses the symbol frequently. It is in keeping with the idea that the order of the macrocosmic world is reflected in the microcosmic world of man. Just as the sun is the ruler of the heavens, so the king is the "sun" on earth, the ruler of the temporal realm. In Henry IV part 1, the image is first used by Prince Hal in Act 1, scene 2. He likens the change that he plans to make in his own behavior to the emergence of the sun from behind the clouds that hide it. He will emerge in his full glory as the heir to the throne, the son/sun of majesty.
Falstaff puns on the words son/sun in Act 2 scene 4, when he says, "If then thou be son to me, here lies the point: why, being son to me, art thou so pointed at? Shall the blessed sun of heaven prove a micher and eat blackberries? . . . Shall the son of England prove a thief and take purses?" The first two references to son and sun prepare the way for the last one, in which both "son" and "sun" are implied.
Henry IV also uses the symbol when he speaks to Prince Hal in Act 3 scene 2. He refers to "sunlike majesty" and the "cloudy" (sullen) men who do not acknowledge the royal presence, like the clouds that obscure the sun.
Henry IV Part 1: Metaphor Analysis