I went and talked to Joan in the studio he was working in today. The one portrait is nearly finished of a school child (my daughter) on her first day of school.
The words above her silhouette are taken from my favourite poem from Rainer Maria Rilke, Ich lebe mein Leben in wachsenden Ringen. Here is a pretty good translation of the poem:
The reason I chose those words is because I believe that all children and particularly my children have been the greatest blessing I have received in my life. So the answer to the question is "a great song" when it comes to what their presence means in my life.