A new Mishna explains how we should vow. If we vow about ending the benefit in a relationship if something does not happen, the vow should end in words explaining that "any vow that I take in the future shall be void". In that way, the vow need not be dissolved.
But how could this work, ask the rabbis? If a person knows that a vow is meaningless, they won't take vows seriously. Do we rely on the Kol Nidre contract, where we dissolve all vows in advance of the coming year, and lightly vow throughout the year?
Rava suggests that in fact we should do just that. We dissolve our vows at the start of the year, but we do not know which vows we will wish to dissolve in advance. Thus each time we make a vow, we must affirm whether or not we agree with our statement. If so, we say, "I am vowing in accordance with my initial intention."
Rabbi Huna bar Chinanna decided to teach this during the Fesitval lecture. Apparently other rabbis were appalled. How can you worry about people taking vows lightly and then encourage them to dissolve their vows in advance?!
Because I lead a congregation in chanting Kol Nidre each year, I am very familiar with the form of that contract. It is always very exciting to learn more about the the history and the meaning behind that very strange and powerful part of our most holy services.