Debra Dean said this quote

Before you either turn away in disgust or wink knowingly at one another, you should know that the artist insists that this is a picture about love. Filial love. The old man has been condemned by the Roman senate to die of hunger, and his daughter has come to his prison cell and offered her breast to feed him. This has nothing to do with with the decorous love or amorous passions one is more accustomed to seeing in a painting. It is raw and wretched and demeaning. In the end, we are physical bodies and every abstract notion about love sinks beneath this fact.