The vow, as carved, is not a wish. It is a contract, and the contract says: not the sensible one, in front of these three, before the light.

MalfoidIt is asking you to do the one thing you have never done in your life, which is be seen wanting something without explaining it first.

PorterAnd if she does not?

CorvinaThen it stands unkept, and an unkept vow on that stone is a debt the house carries for a year and a day, and the house is not strong enough for that.

CorvinaAnd a witness who feels nothing is no witness. Each of the three of you has to be moved by it before dawn or the count does not close.