The Kama Sutra

Even when a stranger sees at a distance a young woman with the marks of nails on her breast,[37] he is filled with love and respect for her.

A man, also, who carries the marks of nails and teeth on some parts of his body, influences the mind of a woman, even though it be ever so firm. In short, nothing tends to increase love so much as the effects of marking with the nails, and biting.

FOOTNOTE: [Footnote 37: From this it would appear that in ancient times the breasts of women were not covered, and this is seen in the painting of the Ajunta and other caves, where we find that the breasts of even royal ladies and others are exposed.]