An oath is of no moment being not took
Before a true and lawful magistrate
That hath authority over him that swears.
Henry had none, but did usurp the place.
Then, seeing ’twas he that made you to depose,
Your oath, my lord, is vain and frivolous.
(1.2.22–27)

Richard addresses these lines to York, arguing the invalidity of the oath his father has just made to let Henry live out his life as king. After making a deal to entail the Crown to York upon Henry’s death, York seems genuinely content to return to his dukedom and wait. When his sons insist that he should seize the Crown anyway, York reminds them that he’s just pledged an oath. But Richard argues that this oath can’t be valid, since he didn’t swear it before a magistrate, whose presence would be required to make it legally binding. Here, Richard shows that he has an acute analytical mind that recalls the sharp intelligence York himself demonstrated in Part 1 and Part 2. Richard’s claim about the invalidity of his father’s oath also foreshadows the many oaths that will be broken throughout Part 3.

Why, love forswore me in my mother’s womb,
And, for I should not deal in her soft laws,
She did corrupt frail nature with some bribe
To shrink mine arm up like a withered shrub,
To make an envious mountain on my back—
Where sits deformity to mock my body—
To shape my legs of an unequal size,
To disproportion me in every part,
Like to a chaos, or an unlicked bear whelp,
That carries no impression like the dam.
And am I then a man to be beloved?
O, monstrous fault, to harbor such a thought!
(3.2.153–64)

These lines come from Richard’s first major soliloquy, where he announces his plan to take the Crown for himself. But before he firmly commits to this plan, we hear Richard think through his reasoning. He knows that his physical abnormalities have made him a monster in other people’s eyes. The result is that love has “forsworn” him, rendering him an outsider from birth. Richard has clearly integrated this image of himself as a monster into his own self-conception. As such, he shows here that he believes himself not just unloved, but unlovable. It is this logic that leads him to conclude that his only option is pursue power: “this earth affords no joy to me / But to command” (3.2.165–66).

Clarence, beware; thou keep’st me from the light—
But I will sort a pitchy day for thee.
For I will buzz abroad such prophecies
That Edward shall be fearful of his life,
And then, to purge his fear, I’ll be thy death.
Henry and the Prince his son are gone; thou, Clarence, art next;
And by one and one I will dispatch the rest,
Counting myself but bad till I be best.
(5.6.85–92)

These are the final lines of Richard’s second soliloquy, which he delivers immediately after murdering Henry in the Tower. When Richard dealt the fatal blow, he cut Henry off in mid-sentence as he delivered a vitriolic diatribe about how Richard’s physical deformity was a sign of spiritual monstrosity. As Henry dies, Richard expresses his agreement with the fallen king’s assessment. He is indeed a monster, and as such he renounces all ties of kinship that might otherwise restrict him. Declaring himself a man alone in the world, with neither father nor brothers, he turns his attention to those former brethren who are now merely obstacles in his path to power. He pledges first to remove Edward and his newborn son from the board, after which he will dispense with George.