Contrast the language used by the Duke and by Brabantio to describe Othello

Brabantio accuses Othello of bewitching his daughter, and airs his racially-charged grievances. He believes nature has made some mistake. Brabantio likens his grief to a flood that "engluts and swallows other sorrows, and is still itself" (I.iii.57-58). His strong objection foreshadows a confrontation between him and his daughter, and if Desdemona does choose to stay with Othello, it seems likely she will risk her father's love.

In Scene III, the Duke declares to Brabantio: "if virtue no delighted beauty lack, your son-in-law is far more fair than black" (I.iii.290-291). Here, black is associated with ugliness, sin, and darkness, and, by extension, blacks are assumed to embody these traits. The Duke plays down Othello's race, saying he is more "fair" - light or just - than "black". This does not mean the Duke is forward-thinking, only that he can vouch for Othello, who does not seem to have the characteristics of his race. It's a backhanded compliment. Light/white/fairness all convey innocence, goodness, etc.; any symbol that is white has these qualities. The juxtaposition of black and white, light and dark shows up again and again in the play, as the colors become symbolic within the story.