King Lear I.i

CORDELIA Unhappy that I am, I cannot heave
My heart into my mouth. I love your majesty
According to my bond, no more nor less.
LEAR How, How, Cordelia. Mend your speech a little,
Lest you may mar your fortunes

From the beginning of the play Lear shows his desire for physical and sensual evidence. He rejects Cordelia's real, impalpable love in favor of an ostensible love that is confirmed through speech, however fake and pretentious it may be. Cordelia loves Lear through her familial bond with him, and is unable to lie for personal gain, but Lear doesn't approve of this as he has no way of confirming it, even though Cordelia was his favorite.
In addition, this passage shows Lear's views on family. Lear cannot make a distinction between the family and the political realm, and the love of his daughters is treated with the same regard as his people. Lear therefore has his daughters speak eloquently of their love not in private, as it could and should have been done, but ceremonously in public. This show of love could have well been done with any of his subjects, perhaps nobles competing for power, had Lear not any children, and thus shows the bleeding of family and political lines by Lear.