Abdu'l-Bahá said this quote

My hope is that the white and the black will be united in perfect love and fellowship, with complete unity and brotherhood. Associate with each other, think of each other, and be like a rose garden. Anyone who goes into a rose garden will see various roses, white, pink, yellow, red, all growing together and replete with adornment. Each one accentuates the beauty of the other. Were all of one color, the garden would be monotonous to the eye. If they were all white or yellow or red, the garden would lack variety and attractiveness; but when the colors are varied, white, pink, yellow, red, there will be the greatest beauty.