The book is well worth reading, both for its themes and for Helprin's powers of prose.
Regarding the latter, consider this passage:
In one of his essays on painting, Alessandro had expressed the opinion that a face cannot adequately be described in words, or even in sculpture, that it was a province exclusively of the painters, that the recognition of a face was wholly dependent upon the ineffably expressed variations of light and color for which language had few words and sculpture no shapes. Of the infinite variety of angles and intersections that make a smile, language has no inkling: not only no words, but not even numbers. Alessandro had speculated for ten printed pages on the helplessness of photographs and many paintings, the terrible inadequacy of statuary and death masks, even the inadequacy in death, of a face itself. Only the great visual artists could describe a face, he had said, and poets would be wise not to try.