波希多尼Posidonius

波希多尼也被称为阿帕梅亚的波希多尼。第一个名字指的是他教书的地方，第二个名字指的是他出生的城镇，奥龙特斯河畔的阿帕梅亚。不能把这两个人当作不同的人。

尽管他出生在叙利亚的阿帕梅亚，波希多尼来自一个希腊家庭，并在希腊传统中长大。他去雅典完成学业，在那里他师从斯多亚派哲学家罗得岛的帕奈提乌斯。波希多尼在西地中海地区广泛旅行，并在旅行中进行了许多与天文学、地理学和地质学相关的科学研究。

公元前100年后不久，波希多尼成为波希多尼斯多葛学派的领袖。在这个职位上，他还在波希多尼担任政治职务。正是在一个政治职位上，作为大使波希多尼，他在公元前87-86年前往罗马。在那里，他遇到了许多他以前认识并教过的人，包括西塞罗。

波希多尼拜访了西门·马里乌斯，这位曾任七次执政官的罗马将军和政治家。西门·马里乌斯于公元前86年1月13日去世，当时波希多尼仍在罗马。在那里，波希多尼与受过希腊传统教育的庞培大帝成为朋友。庞培大帝与波希多尼保持着友谊，并在后来的多次军事战役中前往波希多尼拜访他。

波希多尼的著作无一留存，但关于他的成就已有大量著述，也有大量工作试图从后世作者引用中保存下来的他的著作残篇中重建他的观点。

波希多尼对纯数学做出了一些次要贡献，在那里他被[2]：-

……被引用为某些定义的作者，或对技术术语的观点，例如“定理”和“问题”，以及属于初等几何的主题。

……他写了一部单独的作品来反驳伊壁鸠鲁学派 Zeno of Sidon，后者曾反对“几何原本”的开端，理由是它们包含了未经证明的假设。

他关于天文学的工作通过克莱奥迈季斯 On the Circular Motions of the Celestial Bodies的论著为我们所相当熟悉。这部作品分为两卷，正如托马斯·利特尔·希思所评论的[2]：-

……第二卷那非常长的第一章（几乎占该卷的一半）……大部分似乎是从波希多尼整段照搬过来的。

克莱奥迈季斯在其著作中解释了波希多尼用来计算地球周长的方法。他的方法基于在波希多尼和亚历山大港对老人星（Canopus）的观测。在波希多尼，他观测到老人星触及地平线，而在亚历山大港，它达到7°30′的高度。利用波希多尼与亚历山大港之间5000stadia的距离，这使波希多尼得出地球周长为240000斯塔德（stadia）的数值。这是一个非常精确的数值，但它的得出是由于两个相互抵消的误差。

波希多尼在上述计算中使用的两个数字都不准确。7°30'实际上应为5°15'，而波希多尼到亚历山大港距离的5000斯塔德这一数字也不正确。后来克劳狄乌斯·托勒密通过克莱奥迈季斯的著作告知我们，波希多尼使用了更准确的3750斯塔德作为波希多尼到亚历山大港的距离，但保留了他非常不准确的7°30'，从而得出地球周长为180000斯塔德的值，这个值太小了。然而我们应当注意，Taisbak在[11]中试图证明，将180000斯塔德这个过小的值归于波希多尼是没有根据的。埃拉托色尼在波希多尼之前150年已给出了准确得多的252000斯塔德的值。

波希多尼还计算了月亮的尺寸和距离，以及太阳的尺寸和距离。他对月亮的测量不准确，部分原因是他假设的是圆柱形阴影而非圆锥形阴影。至于他对太阳的计算，奥托·纽格包尔写道[3]：-

（根据克莱奥迈季斯）波希多尼确定太阳尺寸的尝试相当幼稚，使人难以理解为何他的天文学没有被像西塞罗（Cicero）和普林尼这样自称了解喜帕恰斯著作的作者所嘲笑。

至于波希多尼关于知识的观点，他认为[1]：-

……基本原理取决于哲学家，个别问题取决于科学家；并且他认为，在早期人类中，哲学上明智的人管理一切并发现了所有工艺和产业。……对于真正的判断，标准是正确的推理；但训诫、说服、安慰和劝勉是必要的；而对原因而非质料的探究是重要的。

波希多尼撰写了气象学方面的著作，在这一主题上他密切遵循亚里士多德的学说。他提出了解释云、雾、风和雨的理论。他还对霜、冰雹和彩虹发表了看法。闪电和地震引起了他的兴趣，他试图以科学的方式处理所有这些主题，尽管他几乎不可能得出接近正确的解释。

在道德哲学方面，他遵循斯多亚学派的教义，并对美德、邪恶、灵魂和情感发表了见解。他撰写了涵盖约公元前146年至约公元前63年这一时期的历史著作。这些著作叙述了罗马内战以及希腊人和罗马人与其他民族如凯尔特人、日耳曼人以及西班牙和高卢诸民族的接触。

Posidonius of Rhodes is also known as Posidonius of Apameia. The first of these names refers to where he taught while the second refers to the town of his birth, Apameia on the Orontes. One must not think of these two as different people.

Although he was born in Apameia in Syria, Posidonius was from a Greek family and he was brought up in the Greek tradition. He went to Athens to complete his education, and there he studied under the Stoic philosopher Panaetius of Rhodes. Posidonius travelled widely in the western Mediterranean region and he made many scientific studies on his travels relating to astronomy, geography and geology.

Some time not long after 100 BC Posidonius became the head of the Stoic School in Rhodes. While in this position he also held political office in Rhodes. It was in a political position, as ambassador of Rhodes, that he travelled to Rome in 87-86 BC. There he met a number of men whom he had known and taught earlier including Cicero.

In Rome Posidonius visited Gaius Marius, the Roman general and politician who was consul seven times. Marius died on 13 January 86 BC while Posidonius was still in Rome. While there Posidonius became friends with Pompey the Great who had been educated in the Greek tradition. Pompey the Great kept up his friendship with Posidonius and visited him in Rhodes on a number of later occasions when on his military campaigns.

None of the writing of Posidonius has survived but much has been written about his achievements and much work has been undertaken trying to reconstruct his views from the fragments of his writings which are preserved in quotations by later authors.

Posidonius made some minor contributions to pure mathematics where he is [2]:-

... quoted as the author of certain definitions, or for views on technical terms. e.g. 'theorem' and 'problem', and subjects belonging to elementary geometry.

... he wrote a separate work in refutation of the Epicurean Zeno of Sidon, who had objected to the very beginnings of the "Elements" on the ground that they contained unproved assumptions.

His work on astronomy is fairly well known to us through the treatise by Cleomedes On the Circular Motions of the Celestial Bodies. The work is in two volumes and as Heath comments [2]:-

... the very long first chapter of Book II (nearly half of the Book) ... seems for the most part to be copied bodily from Posidonius.

Cleomedes explains in his work the method used by Posidonius to calculate the length of the circumference of the earth. His method is based on observations of the star Canopus at Rhodes and Alexandria. At Rhodes he observes that Canopus touches the horizon while at Alexandria it reaches an altitude of 7° 30'. Using a distance of 5000 stadia between Rhodes and Alexandria this gave Posidonius a value of 240000 stadia for the circumference of the earth. This a very accurate value, but it is produced because of two compensating errors.

Both figures used by Posidonius in the above calculation are inaccurate. The 7° 30' should be really 5° 15' while the figure of 5000 stadia for the Rhodes to Alexandria distance is also incorrect. Later Ptolemy informs us via the writings of Cleomedes, Posidonius used the more accurate 3750 stadia for the Rhodes to Alexandria distance but kept his very inaccurate 7° 30' thus obtaining the figure of 180000 stadia for the circumference which is far too small. We should note, however, that Taisbak in [11] attempts to prove that attributing this far too small value of 180000 stadia to Posidonius is unfounded. Eratosthenes had given a much more accurate value of 252000 stadia 150 years before Posidonius.

Posidonius also made calculations of the size and distance to the moon, and the size and distance to the sun. His measurements of the moon are inaccurate partly because he assumes a cylindrical rather than conical shadow. As to his calculations of the sun, Neugebauer writes [3]:-

Posidonius's attempts (according to Cleomedes) to determine the size of the sun are rather naive and make it difficult to understand that his astronomy was not ridiculed by authors like Cicero and Pliny who pretend to know the work of Hipparchus.

As to Posidonius's views on knowledge he believed that [1]:-

... fundamental principles depended on philosophers and individual problems on scientists; and he believed that, among early men, the philosophically wise managed everything and discovered all crafts and industry. ... For true judgement the standard is right reasoning; but precepts, persuasion, consolation, and exhortation are necessary; and enquiry into causes as opposed to matter is important.

Posidonius wrote on meteorology, a topic where he closely followed the teachings of Aristotle. He gave theories to explain clouds, mist, wind and rain. He also gave opinions on frost, hail and rainbows. Lightning and earthquakes interested him and he tried to approach all these topics in a scientific manner although he had little chance of coming up with explanations which were anywhere close to being correct.

In moral philosophy he followed the Stoic teachings and gave opinions on virtue, evil, the soul, and emotions. He wrote historical works covering the period from about 146 BC to about 63 BC. These works give an account of the Roman civil wars and the contacts by the Greeks and the Romans with other peoples such as the Celts, Germans, and peoples of Spain and Gaul.