During the Renaissance era, artists could not show a woman's toes or feet in their paintings.

Bare feet were not to be shown

Explanation:

In societies that were used to wearing shoes having bare feet was a symbol for many things.  In some cases having bare feet was the same as being unclothed and and represented sexuality, poverty or humility. Bare feet were seen as erotic or shameful. In many European nations and Asian societies such as China the depiction of bare feet we likened to shame, poverty and slavery. In other places it was a sign of erotica and was therefore generally unacceptable.