It is with great sadness that I learned of the passing of Professor Wangari Maathai. On behalf of all Americans, Michelle and I send our deepest condolences to Professor Maathai's family and the people of Kenya at this difficult time. The world mourns with you and celebrates the extraordinary life of this remarkable woman who devoted her life to peacefully protecting what she called "our common home and future." The work of the Greenbelt Movement stands as a testament to the power of grassroots organizing, proof that one person's simple idea--that a community should come together to plant trees--can make a difference, first in one village, then in one nation, and now across Africa. Professor Maathai's tireless efforts earned her not only a Nobel Peace Prize and numerous prestigious awards, but the respect of millions who were inspired by her commitment to conservation, democracy, women's empowerment, the eradication of poverty, and civic engagement. Professor Maathai further advanced these objectives through her service in the Kenyan government, the African Union, and the United Nations. As she told the world, "we must not tire, we must not give up, we must persist." Her legacy will stand as an example to all of us to persist in our pursuit of progress.