Entitled: "The platonic kiss" showing a young woman in her underclothing kissing mirror. Depending on the culture and context, a kiss can express sentiments of love, passion, romance, eroticism, sexual attraction, affection, respect, greeting, friendship, peace and good luck, among many others. In some situations a kiss is a ritual, formal or symbolic gesture indicating devotion, respect, or sacrament. Kissing has been recorded for at least the last five millennia. The study of kissing started some time in the 19th century and is called Philematology. Photographed by William H. Rau, 1901