Jubal Harshaw is a connoisseur of art among other things, but Robert A Heinlein really uses the sculptures of Jubal Harshaw and Jubal's ability to Grok them to the fullest as a way to convey his point about Michael and about the society we live in. The first sculpture, the "Caryatid Who Has Fallen under Her Stone" that Jubal mentions in his sculpture room.
Jubal observes a connection between the lady in the sculpture and Mike. The sculpture is of a woman under the weight of a stone. Mike came to the Earth bearing the weight of having to spread the martian way of life to humanity and having to learn and become accustom to earthling ways. The next sculpture in his collection is, la belle heaulmiere.
This sculpture is of a very old lady and displays the effects of aging. When Ben notices this, Jubal corrects him in saying, "Anybody can see a pretty girl. An artist can look at a pretty girl and see the old women she will become.A better artist can look at an old women and see the pretty girl she used to be. A great artist can look at an old women, portray her exactly as she is...and force the viewer to see the pretty girl that she used to be... more than that , he can make anyone with the sensitivity of an armadillo see that this lovely young girls still alive, imprisoned inside her ruined body".
The last sculpture Jubal mentions, is the Little Mermaid.
The little Mermaid sculpture is a mermaid who chose to become human and is sitting on a rock. Jubal wants to set it up as a memorial to Mike because just like the Little Mermaid, Mike has had to give up a part of himself to become human.