A century and a half ago, an English judge stated: All painters do not paint portraits like

Question:

A century and a half ago, an English judge stated: “All painters do not paint portraits like Sir Joshua Reynolds, nor landscapes like Claude Lorraine, nor do all writers write dramas like Shakespeare or fiction like Dickens. Rare genius and extraordinary skill are not transferable.” What legal doctrine is the judge describing? What is the ethical basis of this rule?