Plato wrote The Republic in around 375 BC, so about 75 years before Euclid wrote The Elements. In this work Plato sets out his ideas about education. For this, he believes, one must study the five mathematical disciplines, namely arithmetic, plane geometry, solid geometry, astronomy, and harmonics. After mastering mathematics, then one can proceed to the study of philosophy. First Plato gives an overview of his educational ideas, then goes on the talk about the five mathematical disciplines. Plato, as narrator, describes a conversation he is having with his elder brother Glaucon, who addresses the narrator as Socrates.柏拉图大约在公元前 375 年写下了《共和国》，因此比欧几里得写《几何原本》早了大约 75 年。在这部著作中，柏拉图阐述了他的教育思想。他认为，人们必须学习五门数学学科，即算术、平面几何、立体几何、天文学和韵律。掌握了数学之后，就可以学习哲学。柏拉图首先概述了他的教育思想，然后继续讲述五门数学学科。柏拉图作为叙述者，描述了他与哥哥格劳孔的对话，格劳孔称呼叙述者为苏格拉底。
Plato's arguments here are similar in nature to those used to advocate the study of arithmetic. It must not be studied for its practical uses but for training the mind.柏拉图在这里提出的论点与主张学习算术的论点性质相似。学习算术不是为了实用，而是为了训练心智。
参考网站https://mathshistory.st-andrews.ac.uk/Extras/Plato_on_mathematics/