The description of Sir James is hysterical. He is an oblivious bro, and Eliot cuts ignorant men like him down to size. 

He's contentedly mediocre: he has "the rare merit of knowing that his talents, even if let loose, would not set the smallest stream in the county on fire." An attractive clever wife would suit him well, could help lead his decisions. Besides, he can always put her in her "place," because, after all, he is a man, and "a man's mind--what there is of it--has always the advantage of being masculine." A man's mind may be SMALL and LIMP but its position in a male frame in a patriarchal society...firms it up, you might say. Gives it the necessary stiffness for even the most ignorant man to have dominance over intelligent women.