Did the Greeks consider colors as capable of acting on psychological states? This study attempts to answer this question by focusing on one particular kind of context: rituals, which create an "emotional commu-nity" by allowing communication with the invisible sphere. The analysis is limited to the three main colors that the Greeks seem to have considered as being most significant, at least according to the epigraphic corpus of ritual norms: white, black, and purple. The objective is to determine whether the Greeks thought these specific colors were able to arouse emotions among both the devotees and the gods. I therefore explore, first, the link between whiteness and joy; then, the connections between blackness and mourning, sadness or anger; finally, the ambivalent affective values of purple. It appears that the same color, loaded with semantic potentialities, can generate different emotions depending on the rituals. In addition, the mode of action of colors must be understood in terms of relation, dynamically; colors causally interact and what really matters is their contrastive value.