A mother who is obsessing about being thin and dieting and exercising is not going to be a very good mother.
It is as absurd to say that a man can't love one woman all the time as it is to say that a violinist needs several violins to play the same piece of music.
The President regards the Japanese as a brave people; but courage, though useful in time of war, is subordinate to knowledge of arts; hence, courage without such knowledge is not to be highly esteemed.