Our podcast episode on him:
A commentator on Pseudo-Democritus and Bishop in what is now Libya.
Also see Neo-Platonism
the earliest known reference to a hydrometer
Bishop, even though he was neo-platonic
Synesius (c. 373 – c. 414), was a Greek bishop of Ptolemais (Modern day Libya) after 410,
Synesius was born of wealthy parents, who claimed descent from Spartan kings who founded Cyrene, at Balagrae (Bayda now) near Cyrene (also in Libya) between 370 and 375.
In the year 393 (when he was 20) he went with his brother Euoptius to Alexandria, where he became an enthusiastic Neoplatonist and disciple of Hypatia. Between 395 and 399 he spent some time in Athens. In addition to being a bishop, he’s now mostly known for his philosophic ideas and poetry.
In 398 he was chosen as an envoy to the imperial court in Constantinople by Cyrene and the whole Pentapolis. He went to the capital in occasion of the delivery of the aurum coronarium and his task was to obtain tax remissions for his country. In Constantinople he obtained the patronage of the powerful praetorian prefect Aurelianus. Synesius composed and addressed to Emperor Arcadius a speech entitled De regno, full of topical advice as to the studies of a wise ruler, but also containing a bold statement that the emperor’s first priority must be a war on corruption and a war on interpenetration of barbarians in Byzantine army.
His three years’ stay in Constantinople was rough; it was there where he had free time to write some of his works.
Aurelianus succeeded in granting him the tax remission for Cyrene and the Pentapolis and the exemption from curial obligations for him, but then he fell in disgrace and Synesius lost everything. Later Aurelian returned in power, restoring his own grants to Synesius. The poet, then, composed Aegyptus sive de providentia, an allegory in which the good Osiris and the evil Typhon, who represent Aurelian and the Goth Gainas (ministers under Arcadius), strive for mastery, and the question of the divine permission of evil is handled.
In 402, during an earthquake, Synesius left Constantinople to return to Cyrene. Along the road he passed through Alexandria, where he returned in 403. Here he married and lived, before returning at Cyrene in 405. The following years were busy, for Synesius. His major concern was the organisation of the defence of the Pentapolis from the yearly attacks of neighbouring tribes.
In 410 Synesius, whose Christianity had until then been by no means very pronounced, was popularly chosen to be bishop of Ptolemais, and, after long hesitation on personal and doctrinal grounds, he ultimately accepted the office thus thrust upon him, being consecrated by Theophilus at Alexandria. One personal difficulty at least was obviated by his being allowed to retain his wife, to whom he was much attached; but as regarded orthodoxy he expressly stipulated for personal freedom to dissent on the questions of the soul’s creation, a literal resurrection, and the final destruction of the world, while at the same time he agreed to make some concession to popular views in his public teaching. His tenure of the bishopric was troubled not only by domestic bereavements (his three sons died, the first two in 411 and the third in 413) but also by the barbarian invasions of the country (in repelling which he proved himself a capable military organizer) and by conflicts with the praeses Andronicus, whom he excommunicated for interfering with the Church’s right of asylum. The date of his death is unknown; it is usually given as c. 414, because he appears to have been unaware of the violent death of Hypatia (his mentor mentioned before).
His many-sided activity, as shown especially in his letters, and his loosely mediating position between Neoplatonism and Christianity, make him a subject of fascinating interest. His scientific interests are attested by his letter to Hypatia, in which occurs the earliest known reference to a hydrometer, and by a work on alchemy in the form of a commentary on pseudo-Democritus.
Among the publications of this period are a treatise On an Astrolabe that he constructed for a friend in Constantinople, an amusing speech In Praise of Baldness (a reply to In praise of hair by Dio Chrysostom). He also published an essay On Dio Chrysostom, a late first-century sophist-philosopher like Synesius, who uses this essay to explain his cultural ideal. His main work in these years, however, was The Egyptian tale, or On Providence, published in 402. It is a romanticized account of his trip to Constantinople, in which two of Arcadius’ ministers are likened to the Egyptian gods Osiris and Seth. In “On an Astrolabe” he makes it clear that arithmatic and astronomy are to be considered absolute truths (he’s a fan of Pythagoras” and hopes to kindle a love of astrology to gain knowldedge.
The earliest known reference to a hydrometer A hydrometer is an instrument used to measure the specific gravity (or relative density) of liquids; that is, the ratio of the density of the liquid to the density of water.