September 18

…you must be very grateful to the whites of America, and the whites must become very loving toward you so that you may progress in all human grades. Strive jointly to make extraordinary progress and mix together completely. In short, you must be very thankful to the whites who were the cause of your freedom in America. Had you not been freed, other blacks would not have been freed either. Now—praise be to God! —everyone is free and lives in tranquillity. I pray that you attain to such a degree of good character and behavior that the names of black and white shall vanish. All shall be called human, just as the name for a flight of doves is dove. They are not called black and white. Likewise with other birds.

I hope that you attain to such a high degree—and this is impossible except through love. You must try to create love between yourselves; and this love does not come about unless you are grateful to the whites, and the whites are loving toward you, and endeavor to promote your advancement and enhance your honor. This will be the cause of love. Differences between black and white will be completely obliterated; indeed, ethnic and national differences will all disappear. 
- ‘Abdu’l-Baha  (From a talk, 23 April 1912, at Howard University, Washington D.C.; ‘The Promulgation of Universal Peace: Talks Delivered by ‘Abdu’l-Bahá during His Visit to the United States and Canada in 1912’)