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Weigel, Erhard (* 1625 †  1699)
Weigel, Erhard (* 1625 † 1699)

Weigel, Erhard (* 1625 † 1699)

Basic Overview Data

1625, Weiden
1699, Jena
Protestant, Lutheran
Institutional Affiliation
University of Leipzig,
University of Jena
Keyword Filters
Protestant, Lutheran, Rationalist
Important Family Relations:
Father, Michael Weigel (1591 - 1637), Clothier, Elementary teacher (Schulmeister)
Nephew, Christoph Weigel (1654 - 1725), Copper engraver
Kanonische URL:


Born 1625 in Weiden a. d. Waldnaab Weigel and his family had to leave that place in 1627 when the town was occupied by imperial troops and subsequently recatholized. He grew up in Wunsiedel in the protestant margraviate Ansbach-Bayreuth. Because of the need of the family Weigel gave private lessons. From 1644 on he visited the Lutheran grammar school in Halle and additionally made his living as the scribe of the astrologist Bartholomäus Schimpfer. From 1647 on he studied arts and especially mathematics at the University of Leipzig and attained the licence of teaching in 1652 by two metaphysical disputations pro loco (for admission to teach) on existence and duration. 1653 he was appointed to a professorship of mathematics at the University of Jena and kept that position up to 1695. In these years he showed a fruitful activity in teaching and research that contributed to the attractiveness of the university in the second half of the 17th century. In addition to his professorship he became court-mathematician to Duke William IV. of Sachsen-Weimar in 1657 and the leading architect of the duchy of Sachsen-Jena in 1662. His close relationship with William IV. and other pillars of the university helped him prevail in the conflicts with his faculty colleagues caused by his understanding of mathematics as the universal science and by his alleged infringements of the domains of other professorships. Weigel’s wide fields of interest also included moral and political philosophy and pedagogy. He is considered a pioneer of the secondary modern school (Realschule) in Germany and undertook a famous school-experiment probing new methods of education. His plan of a Collegium Artis Consultorum, a kind of national academy, inspired Leibniz' foundation of the Berlin academy in 1700. Weigel’s last stage of life was mainly devoted to overcoming the different calculation of time in the German empire caused by the protestant refusal to accept the Gregorian calendar reform. His plan for an improved imperial calendar that slightly modified the Gregorian calendar was finally accepted by the protestant estates and ended the divided calculation of time shortly after Weigel’s death in 1699.

Comment on main natural law works:

Weigel’s wide understanding of the mathematical method as universally applicable to any science also considered natural law as one of its fields of application. In the Analysis Aristotelica ex Euclide restituta of 1658 he developed a scientific theory based on Aristotle's Posterior Analytics reinterpreted in the light of Euclid's Elementa. It considered scientific method as a universally applicable way of demonstrating necessary relations in any given field of knowledge – in contrast to the traditional limitation of Aristotelian Apodeixis to the theoretical disciplines of mathematics, physics and metaphysics. The work contains a chapter on moral philosophy, one part of which is a "Humanarum actionum scientia", demonstrating moral affections of human actions from prime principles and observations, while the other, practical part deals with "the constant inclination of the will to do the good at any occasion in a decent manner". Because of its universal claim of reforming the philosophical disciplines, the work entailed a conflict with Weigel’s faculty collegues and was banned from publication. It reappeared in 1671 and 1672 with an altered title. In the Arithmetische Beschreibung der Moral-Weißheit von Personen und Sachen of 1673 Weigel develops a social philosophy that parallels arithmetical and social relations and in particular numbers with the legal and hierarchical organization, both of which are considered a product of human imposition. The generation of the state is explained by an (putative) social contract, whereby an original "Chaos morale" is overcome by the creation of a "wohl verbundene moralische Welt und bürgerliches Wesen". The moral world does not absolutely depend on human imputation, because its most basic precepts, called natural law, had originally been ordained by God. This natural law is developed from the biological and rational capacities of man in accordance with the stoic and Roman law tradition. The Wienerischer Tugend-Spiegel and the Aretologistica of 1687 develop a virtue-based ethics that considers virtue as an application of calculation ("Rechnen"). Like Hobbes' "computatio" Weigels "Rechnen" does not only denote elementary mathematical operations but any productive reasoning in theory and practice. Unlike Hobbes the moral calculation does not simply consist in rules of self-preservation but is exerted within the framework of an eudaimonistic ethics and mainly serves to define mediocrity as the measure of moral action.

Comment on profile’s conception of natural law:

Weigel shares with other modern natural law thinkers the idea of developing natural law as a demonstrative science (s.a.). He conceives the moral world (ens civile) as a second creation analogous to the first creation, but based in the human will (consensuali hominum imputatione). In that second creation persons, whose essence consists of estimation (Achtbarkeit), and (moral) things, which are constituted by their pertinence to persons, function as moral substances. That world also includes the state that is considered in a Hobbesian manner as product of a putative social contract and as a result of calculation. Its legal and hierarchical organization runs parallel to the position-system of numbers whereby a simple cipher corresponds to an individual or a household, the basis of the number system to an authority and the whole line to a political community. In distinguishing the moral world as a realm of liberty and human responsibility from the natural world Weigel anticipates Pufendorf’s famous distinction of physical and moral entities. According to Wolfgang Röd he has thus approached the idea of an autonomous social philosophy conceiving its relations as normative ones in contradistinction to those of natural philosophy. But that autonomy is relativized by the fact that in his later writings Weigel conceives any finite being as “value” (valor) and as a result of divine imputation. The outcome is an order of being conceived as a hierarchy of divinely imposed values that indifferently comprises natural, moral and notional entities. The hierarchy also serves as the frame of the moral world, whose basic precepts – called natural law – are understood as divine ordinations. Regardless of such voluntarism, natural law is conceived in an essentialist manner according to stoic ideas. In the Arithmetische Beschreibung der Moral-Weißheit von Personen und Sachen (chap. XVII, § 21) Weigel makes a twofold distinction into a law of absolute obligations ("Recht der unumgänglichen Schuldigkeiten", jus naturae primaevum) and a law of voluntary affairs ("Recht der freywilligen doch von der Natur selbst an die Hand gegebenen Geschäffte", jus naturae secundarium). Of the former law one part is based on biological capacities as the care of oneself, self-defence, procreation and support of children; the other part that forms the properly human natural law is based on the rational capacities to worship God, to live honestly, not to injure others and to give to each one his due. It follows the stoic distinction between the “first natural things (prima naturae)” and the rational nature, that Weigel takes from Roman law (Institutions I.i-ii) and not from Hugo Grotius, whose De Jure Belli ac Pacis (Prolegomena) he does not cite in that context. But on the other hand his allusions to a law of nations binding all states in another passage of that work (chap. I, § 7) suggest at least his knowledge of the Dutch author.

The application of natural law to particular cases is accomplished by virtue that does not only require a knowledge of the “naturally right and good”, but also calculation in determining the middle path “mediocrity” between the vices of excess and deficiency. Weigel’s ethics is eudemonistic, i. e. the ultimate end of man is happiness that consists in a life according to virtue which is put into practice by the rational part of the soul, i. e. by calculation. That life is perfected in the state. Though conceived as a “Zusammen-Rechnungsmittel“ and as a product of human invention "Erfindungs-Kraft“ its end is not security but happiness ("Vergnüglichkeit und Hertzensfreude des mit Nothdurffts-Mitteln möglichst versehenen Verstand- und Tugend-übenden Gemüthes“). Weigel thus retains the idea of man as zoon politikon and considers the voluntaristic creation of the moral world only as the means of its realization. Though sharing some facets of the modern natural law tradition like voluntarism and contractualism Weigel’s moral and political philosophy remains in many respects committed to scholasticism.

Academic Data


1647 - 1653, Mathematics, poetry at University of Leipzig [Philipp Müller, Andreas Rivinus]

Academic Degree

1649, Baccalaureus Philosophiae at University of Leipzig
1650, Magister Philosophiae at University of Leipzig
1652, Habilitation at University of Leipzig (Disputatio pro loco)

Academic Travels

1672 - 1672, Germany (Nürnberg 1672 - 1672)
1683 - 1683, Germany (Regensburg 1683 - 1683)
1685 - 1688, Germany (Nürnberg 1686 - 1686, Sulzbach 1687 - 1687, Nürnberg 1687 - 1687), Austria (Vienna 1687 - 1688)
1694 - 1695, Germany (Regensburg 1694 - 1695)
1698 - 1699, Austria (Vienna 1698 - 1699), Germany (Regensburg 1699 - 1699)
1691 - 1691, The Netherlands (Den Haag 1691 - 1691)
1696 - 1697, Denmark (Copenhagen 1696 - 1696), Sweden (Stockholm 1696 - 1697)

Academic Teaching

1675, SS: "Theory of body, proof of divine existence", Public Lecture at University of Jena, Faculty of Philosophy

Professional Data


1650 - 1653, Docent at University of Leipzig, Faculty of Philosophy
1653 - 1695, Professor of Mathematics at University of Jena, Faculty of Philosophy

Titles, Memberships and Other Relevant Roles

1654 - 1695, Alumnorum Inspector, University of Jena, Jena
1657 - 1662\.., Court Mathematician, Ducal Court, Weimar
1662 - 1693\.., Artium Architectonicarum Director Supremus, Ducal Court, Jena
1688 - 1699, Imperial Councillor, Imperial Court, Vienna
../1685 - 1699, Palatine-Sulzbachian Councillor, Palatine Court, Sulzbach-Rosenberg

Printed Sources


Analysis Aristotelica ex Euclide restituta, Genuinum Sciendi modum, & Nativam restauratae Philosophiae faciem per omnes Disciplinas & Facultates ichnographicè depingens, (Jena: Grosius, 1658): Digital Version.
    - Edition 1671 (Jena: Meyer): Digital Version.
    - Edition 1672 (Leipzig: Grosius).
    - Critical Edition 2008 (Stuttgart-Bad Cannstatt: Frommann-Holzboog).

Universi Corporis Pansophici Prodromus de Gradibus Humanae Cognitionis, ipfaque Trina Mentis operatione, generaliter agens, Quem dicere posses Pantognosiam, (Jena: Bauhofer, 1672): Digital Version.
    - Critical Edition 2003, (Stuttgart-Bad Cannstatt: Frommann-Holzboog).

Corporis Pansophici Pantologia, De Unoquovis in genere non tantùm, sed & de singulorum tum Naturalium tum Artefactorum, Speciebus, (Jena: Bauhofer, 1673): Digital Version.
    - Critical Edition 2003, (Stuttgart-Bad Cannstatt: Frommann-Holzboog).

Arithmetische Beschreibung der Moral-Weißheit von Personen und Sachen / Worauf das gemeine Wesen bestehet / Nach der Pythagorischen CreutzZahl in lauter tetractysche Glieder eingetheilet, (Jena: Bielcken, 1674): Digital Version.
    - Critical Edition 2004, (Stuttgart-Bad Cannstatt: Frommann-Holzboog).

Wienerischer Tugend-Spiegel (Nürnberg: Endtern, 1687): Digital Version.
    - Edition 1721 (Nürnberg: Endtern): Digital Version.
    - Critical Edition 2016, (Stuttgart-Bad Cannstatt: Frommann-Holzboog).


Farrago Quaestionum Politicarum de Republica, (Leipzig:Lanckisch, 1652),
[Praeses: Erhard Weigel, Respondent: Heinrich Weidemann]: Digital Version.

Genuinum Societatis Civilis Scopum Excerptis Quibusdam Mathematicis Praefixum, (Jena: Werther, 1662), [Praeses: Erhard Weigel, Respondent: Friederich Nitsche].

Dissertationem ... Politicam ... De Ratione Status, (Jena: Krebs, 1667), [Praeses: Erhard Weigel, Respondent: Philipp Otto Gercken]: Digital Version.

De Jurejurando Specimen Academicum, (Jena: Gollner, 1675), [Praeses: Erhard Weigel, Respondent: Hendrik Vockestaert]: Digital Version.

Manuscript Sources


Unterthänigstes Memorial ... Wegen des Aristotelisch-Euclidischen Tractats / Memorial, directed to Duke Wilhelm IV. of Sachsen-Weimar, (Jena, 2. August 1658), [Landesarchiv Thüringen - Hauptstaatsarchiv Weimar: A 7727, Bl. 3r-3v.].

Demand of a salary increase (Jena 1665), [LATh-HStA Weimar: A 6077, Bl. 401].

Weigels Revocation of his proof of Trinity from arithmetic principles (Jena, 27. September 1679), [LATh-HStA Weimar: A 5519, Bl. 137r-138r].

For further information on manuscript sources see:
    - Hermann Schüling: Erhard Weigel (1625-1699). Materialien zur Erforschung seines Wirkens, (Giessen: Universitätsbibliothek, 1970), p.86f: Download
    - Hildegart Schlee: Erhard Weigel und sein süddeutscher Schülerkreis. Eine pädagogische Bewegung im 17. Jahrhundert, (Heidelberg: Quelle & Meyer, 1968), pp. 144f.
    - Christa Schaper: "Neue archivalische Forschungen zur Lebensgeschichte von Professor Erhard Weigel (1625-1699)", in: Archiv für Geschichte von Oberfranken, 39, (Bayreuth: Historischer Verein für Oberfranken,1959), S. 97-140.
    - Erhard-Weigel-Gesellschaft / Forschung / Werk und Quellen.


A critical edition of the profile's correspondence does not yet exist. A list of the correspondence (metadata) can be found on the homepage of the Erhard-Weigel-Gesellschaft.

Parts of the correspondence have been published in the edited correspondences of some of his disciples and other contemporary authors:  
    - Schmidt-Biggemann, Wilhelm (ed.): Samuel Pufendorf: Gesammelte Werke, Bd. 1: Briefwechsel, edited by Detlef Döring, (Berlin: Akademie-Verlag, 1996), Letters No. 8, 17. April 1659, p. 141, 150: Digital Version
    - Leibniz-Forschungsstelle (ed.): Gottfried Wilhelm Leibniz: Sämtliche Schriften und Briefe, (Berlin: Akademie-Verlag)
        - Part II.1: Download, No. 212, 215.
        - Part II.2: Download, No. 263.
        - Part III.6: Download, No. 24, 36.

Direct Personal Connections:

1659, Wilhelm von Schröder, Jena [Student of Weigel]
1656, Samuel Pufendorf, Jena [Student of Weigel]
1663, Gottfried Wilhelm Leibniz, Jena [Student of Weigel]
1672, Gottfried Klinger, Jena [Student of Weigel]
1679, Johann Paul Hebenstreit, Jena [Student of Weigel]
Mikkel Munthe Jensen, Last Update:  17.03.2021