上句见：Day329
The Story of Philosophy《哲学的故事》第1章Plato第6节VI. The Psychological Problem第5段第4句：

Now just as effective individual action implies that desire, though warmed with emotion, is guided by knowledge; so in the perfect state the industrial forces would produce but they would not rule; the military forces would protect but they would not rule; the forces of knowledge and science and philosophy would be nourished and protected, and they would rule. Unguided by knowledge, the people are a multitude without order, like desires in disarray: the people need the guidance of philosophers as desires need the enlightenment of knowledge. "Ruin comes when the trader whose heart is lifted up by wealth, becomes ruler"(434); or when the general uses his army to establish a military dictatorship. The producer is at his best in the economic field, the warrior is at his best in battle; they are both at their worst in public office; and in their crude hands politics submerges statesmanship. For statesmanship is a science and an art; one must have lived for it and been long prepared. Only a philosopher-king is fit to guide a nation. "Until philosophers are kings, or the kings and princes of this world have the spirit and power of philosophy, and wisdom and political leadership meet in the same man, … cities will never cease from ill, not the human race"(473).
浙江大学译本：生产者在经济领域中得心应手，战士在战场上如鱼得水，但就公共权力而言，生产者和战士都是极糟糕的人选；在他们那粗糙的手中，政治才能将被政治权术淹没。

解析

1、The producer is at his best in the economic field, the warrior is at his best in battle;
生产者在经济领域得心应手，战士则在战场上如鱼得水；
warrior: a person who fights in battles and is known for having courage and skill（尤指旧时的）勇士，武士
Most of these soldiers were Germans who, as you know, were excellent warriors.多数士兵是日耳曼人，你是知道的日耳曼人是很好的武士。《世界小史》
2、they are both at their worst in public office;
但就公职而言， 这两种人都是最糟糕的人选；
at their worst: as bad or unpleasant as someone or something can be 极其糟糕
When my eyes were at their worst that unhappy winter, I accepted an invitation to address a group of undergraduates. 在那个不幸的冬天，当我的眼睛处于最糟糕的状态时，我接受了一个邀请，要去给一群本科生发表演讲。《人性的优点》
3、and in their crude hands politics submerges statesmanship.
在他们那些粗糙的手中，政治才能被政治权术淹没。
submerge: to make (someone or something) go under the surface of water or some other liquid使淹没
Much of Northern Europe could be submerged, the Netherlands would vanish under water.北欧部分地区将被淹没，荷兰将消失在水下。《环境与科学》

这句用了对比、排比及隐喻的手法生动地描述了生产者与战士非公职人选。at one's best与at one's worst指出这两种人的优势与劣势，他们只会用权术而不是政治才能来统治国家。同时还用了“submerge”暗示政治氛围不好，都是权谋在当权。

生产者在经济领域得心应手，战士则在战场上如鱼得水；但就公职而言， 这两种人都是最糟糕的人选；在他们那些粗糙的手中，政治才能被政治权术淹没。