Early patterns of prejudice based on colour reveal the existence of race thinking long before the emergence of modern racism, and clearly demonstrate the beginnings of centuries-long traditions wherein skin colour served to greater or lesser degrees as the badge of master and subject, of the free and enslaved, and of the dominators and the dominated. Words and phrases (such as "a dark day" or a "black heart") are used to equate bad, depressing, or negative conditions with darkness in a way that is offensive to those of darker skin.