Erhard Weigel
Erhard Weigel byPietro della Vecchia
Born	(1625-12-16)16 December 1625 Weiden in der Oberpfalz,Electorate of Bavaria
Died	20 March 1699(1699-03-20) (aged 73) Jena,Saxe-Weimar
Education	University of Leipzig (M.A., 1650;Dr. phil. hab. 1652)[3]
Scientific career
Fields	Mathematician,astronomer andphilosopher
Institutions	University of Jena
Theses	De ascensionibus et descensionibus astronomicis dissertatio (Astronomical dissertation on risings and settings) (1650) Dissertatio Metaphysica Prior (De Existentia); Dissertatio Metaphysica Posterior (De Modo Existentiae, qui dicitur Duratio) (1652)
Academic advisors	Philipp Müller (1650 thesis advisor)[1]
Notable students	Gottfried Wilhelm Leibniz[2] Samuel von Pufendorf

Erhard Weigel (German:[ˈeːʁhaʁtˈvaɪɡl̩]; 16 December 1625 – 20 March 1699) was a Germanmathematician,astronomer andphilosopher.

Weigel earned hisM.A. (1650) and hishabilitation (1652) from theUniversity of Leipzig. From 1653 until his death he was professor of mathematics atJena University. He was the teacher ofLeibniz in summer 1663,^[2] and other notable students. He also worked to make science more widely accessible to the public, and what would today be considered a populariser of science.

He concurred with Jakob Ellrod's "Mittel-Calendar",^[4] and with the advocacy ofLeibniz and others, that the date ofEaster should be based on the astronomical measurement of thespring equinox and the next fullmoon. He followed Jakob Ellrod to theImperial Diet inRegensburg to advocate the use of the Mittel-Calendar or NewGregorian calendar.

• 1625 born inWeiden in der Oberpfalz, son of clothier Michael Weigel and Anna Weigel
• 1627–28 seizures of theUpper Palatinate through imperial troops starting with recatholicization; escape of the Weigel family fromWunsiedel toAnsbach-Bayreuth
• 1638–44 teen years at grammar school in Wunsiedel
• 1644–46 Lutheran high school inHalle (Saale) and simultaneous activity with the astronomerBartholomäus Schimpfer, who teaches him mathematics
• 1646 temporary return to Wunsiedel; mathematics and astronomy instruction with archdeacon Jakob Ellrod
• 1647–50 studies at theUniversity of Leipzig
• 1650MA in philosophy:De ascensionibus et descensionibus astronomicis dissertatio (Astronomical dissertation on risings and settings)
• 1652habilitation in Leipzig withDissertatio Metaphysica Prior (De Existentia); Dissertatio Metaphysica Posterior (De Modo Existentiae, qui dicitur Duratio)
• 1653 post as mathematics professor at theUniversity of Jena
• 1653 (16 July) begins lecturesDe Cometa Novo (regarding the comet of December 1652)
• 1653 (12 September) marries Elisabeth Hartmann (a widow)
• 1654 appointment asStipendiarorum et Alumnorum Inspector (supervision over the Collegium Jenense)
• 1658 publishes the analysisAristotelica ex Euclide restituta, genuinum sciendi modum, & nativam restauratae Philosophiae faciem per omnes disciplinas & facultates ichnographicè depingens; the work brings him into conflict with the philosophical faculty
• 1660 publishesTheodixis Pythagorica (revised edition 1675)
• 1661 publishesHimmelsspiegels (Speculum Uranicum / Aquilae Romanae Sacrum...)
• 1663Gottfried Wilhelm Leibniz, studies one semester in Jena, among others under Erhard Weigel
• 1664 publishes of theSpeculum Temporis Civilis, containing explanation of the calendar
• 1665 publishesSpeculum Terrae
• 1667–70 Weigel's house, in Jena, for its time has remarkable technical interior facilities—among others an elevator and a water pipe
• 1669 publishesIdea Matheseos Universae cum Speciminibus Inventionum Mathematicarum
• 1673 publishesUniversi Corporis Pansophici Caput Summum
• 1673 publishesTetractys, Sumum eum Arithmeticae eum Philosophiae discursivae Compendium
• 1674 publishes an arithmetic description of moralsArithmetische Beschreibung der Moral-Weissheit von Personen und Sachen worauf das gemeine Wesen bestehet
• 1679 Weigel's work on "the mystery of Holy Trinity demonstrated from the principle of geometry", brings him in conflict with the theological faculty and he is forced to retract his work
• 1683 wife Elisabeth dies
• 1688 appointed imperial advisor
• 1691 goes to England to describe research results to the Royal Society, but only reaches the coast where the weather prevents crossing the British Channel
• 1691 calls on the Dutch naturalistChristiaan Huygens at his estate
• 1693 publishesPhilosophia Mathematica, Theologia Naturalis Solida
• 1695 becomes chancellor of the University of Jena
• 1699 dies in Jena

(Source:^[3])

Weigel was arguably one of the earliest German PhD holders.^[3]

Through Leibniz, Weigel is the intellectual forefather of a long tradition of mathematicians and mathematical physicists that connects a great number of professionals to this day (see Academic genealogy of theoretical physicists: Erhard Weigel). TheMathematics Genealogy Project lists more than 50,000 "descendants" of Weigel's, includingLagrange,Euler,Poisson and severalFields Medalists.

The craterWeigel on theMoon is named after him. In 1999 a colloquium was held in Jena on the 300th anniversary of his death.

• Doctor of Philosophy: History

• Katharina Habermann, Klaus-Dieter Herbst (Hrsg.):Erhard Weigel (1625–1699) und seine Schüler. Beiträge des 7. Erhard-Weigel-Kolloquiums 2014. (Göttingen [Niedersachsen]) : Universitätsverlag Göttingen, 2016. – 376 pp.ISBN 978-3-86395-259-4.
• Stefan Kratochwil, Volker Leppin (Hrsg.):Erhard Weigel und die Theologie. [Vorträge des 3. Erhard-Weigel-Kolloquiums, Jena, 11. & 12. Dezember 2003], Berlin: LIT-Verlag, 2015 (Arbeiten zur Historischen und Systematischen Theologie, Band 12),ISBN 978-3-8258-1393-2.
• Schielicke, Reinhard E. et al., 1999,Erhard Weigel - 1625 to 1699. Baroque patriarch of the early German Enlightenment. Proceedings of the colloquium held in Jena on March 20, 1999, on the occasion of the 300th anniversary of his death (=Acta Historica Astronomiae, vol. 7).
• Reinhard Breymayer:Astronomie, Kalenderstreit und Liebestheologie. Von Erhard Weigel und seinem Schüler Detlev Clüver über Friedrich Christoph Oetinger und Philipp Matthäus Hahn zu Friedrich Schiller, Johann Andreas Streicher, Franz Joseph Graf von Thun und Hohenstein, Mozart und Beethoven. Dußlingen : Noûs-Verlag Thomas Leon Heck 2016. - 227 pp. -ISBN 978-3-924249-58-8.

• Behme, T. (2019). "Erhard Weigel's Proof of the Existence of God and its Critique by Leibniz".Studia Leibnitiana51(2), pp. 247–264.

• Erhard Weigel at theMathematics Genealogy Project

• 1625 births
• 1699 deaths
• People from Weiden in der Oberpfalz
• 17th-century German philosophers
• 17th-century German mathematicians
• 17th-century German astronomers
• Leipzig University alumni
• Academic staff of the University of Jena

• CS1 German-language sources (de)
• Articles with short description
• Short description is different from Wikidata
• Articles with hCards
• Pages using infobox person with deprecated parameters
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