The goddess Latona, Jupiter's lover, was banished by jealous Juno. She then gave birth to the twins Apollo and Diana.
     The incident represented in the painting is explained by the experience which an ancient is supposed to have related thus:

    “ Some countrymen of Lycia once insulted the goddess Latona, but not with impunity. When I was young, my father, who had grown too old for active labors, sent me to Lycia to drive thence some choice oxen, and there I saw the very pond and marsh where the wonder happened. Near by stood an ancient altar, black with the smoke of sacrifice and almost buried among the reeds. I inquired whose altar it might be, whether of Faunus or the Naiads, or some god of the neighboring mountain, and one of the country people replied, ‘No mountain or river god possesses this altar, but she whom royal Juno in her jealousy drove from land to land, denying her any spot of earth whereon to rear her twins.
      Bearing in her arms the infant deities, Latona reached this land, weary with her burden and parched with thirst. By chance she espied in the bottom of the valley this pond of clear water, where the country people were at work gathering willows and osiers. The goddess approached, and kneeling on the bank would have slaked her thirst in the cool stream, but the rustics forbade her. “Why do you refuse me water?” said she; “water is free to all. Nature allows no one to claim as property the sunshine, the air, or the water. I come to take my share of the common blessing. Yet I ask it of you as a favor. I have no intention of washing my limbs in it, weary though they be, but only to quench my thirst. My mouth is so dry that I can hardly speak. A draught of water would be nectar to me; it would revive me, and I would own myself indebted to you for life itself. Let these infants move your pity, who stretch out their little arms as if to plead for me;” and the children, as it happened, were stretching out their arms.
      “‘Who would not have been moved with these gentle words of the goddess? But these clowns persisted in their rudeness; they even added jeers and threats of violence if she did not leave the place. Nor was this all. They waded into the pond and stirred up the mud with their feet, so as to make the water unfit to drink. Latona was so angry that she ceased to mind her thirst. She no longer supplicated the clowns, but lifting her hands to heaven exclaimed, “May they never quit that pool, but pass their lives there!” And it came to pass accordingly.
      They now live in the water, sometimes totally submerged, then raising their heads above the surface or swimming upon it. Sometimes they come out upon the bank, but soon leap back again into the water. They still use their base voices in railing, and though they have the water all to themselves, are not ashamed to croak in the midst of it. Their voices are harsh, their throats bloated, their mouths have become stretched by constant railing, their necks have shrunk up and disappeared, and their heads are joined to their bodies. Their backs are green, their disproportioned bellies white, and in short they are now frogs, and dwell in the slimy pool.”