In King Lear, Shakespeare shows the king's harsh, arrogant conduct in act 1, scene 1. This is when he makes the statement "Nothing will come of nothing" to Cordelia. In fact, it is Goneril and Regan who are "empty-hearted," as Kent remarks when he points out the "hollowness" of their speeches. It is these two daughters who truly feel nothing for their father.
Lear then has the rest of the play to reflect on his mistakes, including this one, though it takes him quite some time to begin this process of self-examination. It is the Fool who keeps pushing him to see how he has been the author of his own misfortune, and he does so partly by inviting him to reexamine the idea of "nothing." When Kent complains that one of the Fool's rhymes means nothing, he responds:
Then 'tis like the breath of an unfee'd lawyer; you gave me nothing for't. Can you make no use of nothing, nuncle?
Lear gives a variation on his original reply to Cordelia, saying "nothing can be made out of nothing," to which the Fool tartly responds that "so much the rent of his land comes to."
Goneril and Regan felt nothing for their father and, between them, received a kingdom in return. Cordelia felt something but said nothing and therefore received nothing. At the beginning of the play, Lear's attitude to his daughters' love and his land is like a commercial transaction: he gives away the country in return for flattering speeches. These, he quickly finds, were worth nothing, meaning that he is left with nothing. Indeed, as the Fool perceptively points out, a man who was a king but has given up everything that made him a king has himself become nothing. It is when Lear understands this that he begins to gain wisdom after a lifetime of folly. Understanding what is something (that is, what has solidity and value) and what is nothing is the beginning of self-knowledge for Lear. The same is true of Gloucester, who makes a similar mistake in relation to his two sons.