In 1828, an American artist named Sarah Goodridge painted a portrait of her own breasts and sent it to lawyer-politician Daniel Webster, who had recently become a widower. It is considered the earliest case of someone sending nudes.

From Wikipedia :

Although Goodridge was aged forty when she painted this miniature, according to art critic Chris Packard her breasts seem younger, with a "balance, paleness, and buoyancy" which is imbued in part by the harmony of light, color, and balance.

The American art critic John Updike suggests that the artist intended it to offer herself to Webster; he writes that the bared breasts appear to say "We are yours for the taking, in all our ivory loveliness, with our tenderly stippled nipples".

Love how it is critics' job to quote even on that...