Colors

Mrs. Parsons had a red shawl and one day she asked the Master the significance of the color. He replied that “red expressed activity, but if taken to extremes could stimulate war.” Of the other colors, ‘Abdu’l-Bahá said that “Green expressed joy, yellow was indicative of love, blue promoted thought and black expressed sorrow.” He added that one should wear black only as a convenience, because it does not soil easily.
(Earl Redman, ‘Abdu’l-Bahá in Their Midst, p. 154)