Seizing Gaunt's Lands
After exiling Bolingbroke, Richard decides to seize all of Gaunt's property and wealth for his own. Though his advisors plead with him not to do so, he goes through with his decision thinking that it will bolster his power. However, this move is precisely the reason that Bolingbroke decides to raise and army, invade England, defend what is lawfully his, and depose Richard as king.
Inheritance Law
Richard's advisors warn Richard that if he goes through with his decision to seize Gaunt's estate, he will be in violation of the law, which states that one's estate goes to their firstborn son (in this case, Bolingbroke). Richard is warned that by breaking the law in this specific way – defying the importance of inheritance – he would be calling his own reign into question, as kings inherited the throne from their fathers. Of course, this is precisely what happens after Richard refuses to listen to his advisors and seals his own fate.
Rising and Setting
Throughout the play, as in most history plays, Richard is compared to a sun. This metaphor was often used when describing English kings, as it was meant to convey power and majesty. However, Richard II is one history play that turns this metaphor upside-down, comparing Richard frequently to a setting (rather than rising) sun, one whose power is diminishing as Bolingbroke approaches.
Sight
Once Richard is deposed, he becomes a penniless prisoner who suffers a great deal for his loss. Many characters remark about his tears, how they are so numerous that he is effectively "blinded" by them. However, toward the end of the play, Richard's suffering is presented as the precise phenomenon that makes him "see" more clearly. Thus, his blinding tears are what lend him greater insight into the nature of leadership and one's kingly legacy.