This panel is one of the four surviving altars of the Church of San Barnaba. St. Augustine is depicted walking on a deserted shore, meditating on the mystery of the Holy Trinity and how to explain her flock. Seeing the boy digging a hole, he asks what she is for.
The child responds that he wants to scoop up the ocean; Augustine with a smile says that this is impossible. It is no more impossible than solving the issue that you are occupied with, the boy answers and disappears. In the time of Botticelli, artists often translated such stories into a visual form, thus acting as popularizers of social ideas.
Related Paintings 
St. Augustine, writing in his cell by Sandro Botticelli 
St. Augustine the Blessed by Sandro Botticelli 
The Altar of St. Barnaby by Sandro Botticelli 
Vision de Saint Augustin – Sandro Botticelli 
Extracting the Heart of Saint Ignatius by Sandro Botticelli 
The altar of San Marco, or the Coronation of Mary with the angels, the Evangelist John and St. Augustine, Jerome and Eligius by Sandro Botticelli 
Altar image from the church of Sant Agostino: St. Augustine by Piero della Francesca 
Transformation by Sandro Botticelli
St. Augustine, writing in his cell by Sandro Botticelli St. Augustine the Blessed by Sandro Botticelli The Altar of St. Barnaby by Sandro Botticelli Vision de Saint Augustin – Sandro Botticelli Extracting the Heart of Saint Ignatius by Sandro Botticelli The altar of San Marco, or the Coronation of Mary with the angels, the Evangelist John and St. Augustine, Jerome and Eligius by Sandro Botticelli Altar image from the church of Sant Agostino: St. Augustine by Piero della Francesca Transformation by Sandro Botticelli