I won't speak for very long. After all, it makes little sense to spend much time describing why we're celebrating and not engage in the fun of the celebration itself. So, just two observations.
Actually, it really doesn't matter if we look at six days or at a hundred billion years. From nothing to something is still a factor of infinity, of infinite wonder, something miraculous.
In the cycle of our calendar we started four days ago with the ninth of Av, a date which more than any other commemorates the nothingness that B'nei Yisrael could have become, several times over. A nothingness which might have come about, on more than one occasion, because of narrowminded pettiness on a grand scale, of abandoning universal Jewish values in favor of sectarian power-plays. In two days, we celebrate Tu B'Av in part because of its connection to national reconciliation. It is important for us to remember that we become whole not because we are homogenous, but because we appreciate our differences while we celebrate our core common values.
We appreciate these differences not by ignoring them, but by understanding them. And so, I always hope that as you celebrate your birthday on Tu b'Av, you appreciate the rainbow of different approaches to life within the nation of Israel. Though your mother and I are your parents and you have many very special loved ones, as the only sabra in our family you will always have a bond with other sabras, who come from so many different ethnic backgrounds - Yemen, Poland, Morocco, India, France, the United States, Sweden, etc. You perhaps have an extra helping of the connection to this land we all love and, as such, may have a special appreciation for our need to live as a diverse nation in harmony - within this land that has known so much sadness and joy
It is impossible to make personal decisions without feeling. It is impossible to personally value an object or an idea without feeling. Cognitive science has also, by and large concluded that it is impossible to divorce thought itself from emotional imperatives.
Tamar, two qualities which characterize you are your ability to excel in matters of reason, including mathematics and science, and your strong feelings for things issues that are important to you. You express these emotions so gracefully in song, in dance, and in the wayİyou learned to read the Torah, and I hope you never stop expressing yourself in these ways.
Not so long ago, lots of people thought emotions were the stuff of weakness and should be hidden. While strong passion can cause havoc for the person who cannot control them, strong passion can be the source of infinite strength and determination for the person who can appreciateits power. Tamar, I hope that your emotional and your rational qualities continue to grow in harmony. I hope that you never forget the power, the beauty, and the necessity of your feelings in helping you chart the course of your life. I hope that the wellspring of these feelings, what you hold to be important, will include the values of justice and kindness and love of one's brothers and sisters that you find in Judaism. At the same time, I hope that your powers of reason will help you to sometimes be introspective, something we all need to do occasionally, to make sure that your emotive power is serving the values you hold.
Among God's gifts to human beings are both the intellect to make decisions and a world in which we must make hard decisions. Do not shy away from these decisions and do not doubt your own capacity to make good decisions, to try creative solutions. I have little doubt that you will continue to make us very, very proud.