上句见：Day77
The Story of Philosophy的第78句：第1章Plato第1节The Context of Plato第6段第4句：

At first this philosophy was physical; it looked out upon the material world and asked what was the final and irreducible constituent of things. The natural termination of this line of thought was the materialism of Democritus(460-360 B.C.) — “in reality there is nothing but atoms and space.” This was one of the main streams of Greek speculation; it passed underground for a time in Plato’s day, but emerged in Epicurus(342-270), and became a torrent of eloquence in Lucretius(98-55 B.C.). But the most characteristic and fertile developments of Greek philosophy took form with the Sophists, traveling teachers of wisdom, who looked within upon their own thought and nature, rather than out upon the world of things. They were all clever men (Gorgias and Hippias, for example), and many of them were profound (Protagoras, Prodices); there is hardly a problem or a solution in our current philosophy of mind and conduct which they did not realize and discuss. They asked questions about anything; they stood unafraid in the presence of religious or political taboos; and boldly subpoenaed every creed and institution to appear before the judgementseat of reason. In politics they divided into two schools. One, like Rousseau, argued that nature is good, and civilization bad; that by nature all men are equal, becoming unequal only by class-made institutions; and that law is an invention of the strong to chain and rule the weak. Another school, like Nietzsche, claimed that nature is beyond good and evil; that by nature all men are unequal; that morality is an invention of the weak to limit and deter the strong; that power is the supreme virtue, and the supreme desire of man; and that of all forms of government the wisest and most natural is aristocracy.
浙江大学译本：但古希腊哲学最具代表性、最富生命力的篇意成形于智者学派，他们是云游四方的智慧大师。他们重视内省，考量自身的思想和本质，而非外在的物化世界。

解析

这句主要讲古希腊的智者学派。
1、But the most characteristic and fertile developments of Greek philosophy took form with the Sophists,
But有点先抑后扬的感觉，用原子论来突出后面的古希腊哲学。
characteristic：typical of a person, thing, or group : showing the special qualities or traits of a person, thing, or group明显的，显著的
It points out the unusual characteristics of the key people who helped the company succeed.它指出那些帮助公司成功的关键人物拥有的独特个性。
fertile：producing many ideas多产的
The conspiracy he's describing is a product of his obviously very fertile imagination.他说的那些阴谋猜想全是因为他天马行空的想象力。
take form：to begin to develop : to start to exist or be seen开始成型
The new stadium is gradually taking form. [=being built]

2、traveling teachers of wisdom,
对智者学派的概要介绍：巡回传授智慧的教师。

3、** who looked within upon their own thought and nature,**
进一步讲解智者派关注点是内省自己的思想及本性。
look upon 是一个常用短语，表示“看待”或“考虑”。

4、rather than out upon the world of things.
而不关注外在物化世界。

不过，最具特色和最多产的古希腊哲学来自智者学派，他们是些巡回传授智慧的教师，更多审视自己的思想及本性，而不是外在的物化世界。