i can think of two ways for interpreting the figure of a speech in the first verse. "learning's bower" can refer to "school". A "boy" would no longer like to go or "sit" in a school because of the "cruel eye" of his parents that replaces the joy of studying with dismay. however, this figure can refer not just to "school" but to every place where knowldege is pursued. in that broader sense, philosophically we can question the mentality formed wrongly which seizes or resricts knowledge quest in an institution "i.e. schools". parents always dream of their children having great future. And that "best fucture" is always regarded, according to their mentality, materialistically as an equal to money and thus joy which is achieved primarly through getting a paper, i.e. certificate, form an institution. in brief, spirituality is gone. so "dreary shower", that renders the "bower" worn, refer to such mentality which stole and stealing all the joy of learning because the ultimate goal is no longer exist.