Adolf Ulrik Wertmüller (1751-1811), Danaë and the Shower of Gold, 1787.
In Greek mythology, Danaë was the mother of Perseus. As a girl Danaë’s father received an oracle that his daughter’s son would one day kill him, so he locked his daughter away in a tower, so she would never get pregnant. Because she was so beautiful, Zeus decided to visit her in the form of golden rain or dust, and impregnated her.
This particular painting is just one example of many of how context was so important to older paintings. While an average naked woman might be seen as scandalous, a nude woman from mythology of literature was completely acceptable. She had to be naked because the myth called for it— therefore it couldn’t be pornographic. Danae is a popular subject for overtly sexual paintings like this one because the subject matter is sexual, like the myth of Leda and the Swan. Danaë and Venus or Aphrodite are very popular for overtly sexual paintings, as a quick google search will show (keeping in mind these are hundreds of years old in most cases!). Other mythological ladies and men do appear nude quite frequently but it’s not always so clearly meant to be pleasing a certain audience.
It’s also interesting to note that during the renaissance several artist’s (like Titian and Artemesia Gentileschi) used the image of Danaë to comment on the culture of prostitutes at the time.