Not a birthday boy: some thoughts on Renaissance birth dates

Yesterday,one of the websites that I read on a regular basis informed me that the notorious Renaissance physician Theophrastus of Hohenheim, better known as Paracelsus, was born on 1st May 1493 a claim that I found interesting as I’m currently preparing a public lecture on Paracelsus that I shall be holding in Nürnberg in October. When I stumble across a birth date claim I always cross-reference it with other sources, not actually necessary in this case, as I knew with certainty that the statement was wrong. English Wikipedia gives Hohenheim’s date of birth as 11th November or 17th December 1493 whereas German Wikipedia states ‘supposedly’ 10th November 1493 a date also given by one of two biographical encyclopaedias that I own. The other one gives the correct answer, which is late 1493 or early 1494. Other sources give 24th December 1493 and the Dictionary of Scientific Biography gives ca. 1493 [or 1st May 1494?].


Only known portrait of Paracelsus by Hirschvogel 1540 Source: Wikimedia Commons

The original claim that provoked this post is completely wrong. There is no known registration or record either of Hohenheim’s birth or his baptism and the only information that we have on the subject comes from the record of his death. He died on 24th September 1541 not having completed the 48th year of his life. Assuming that this claim is true then he was born sometime between 25th September 1493 and 25th September 1494. Because of the wording of the record of his death it is usually assumed that he was most probably born in the last third of 1493 or the first third of 1494. All of the specific dates of birth available in the literature were set in the world by authors writing well after his death and based on nothing more concrete than hearsay and thus have no historical validity.

Of particular interest is the claim that he was born on 10th November, as this is the birth date of Martin Luther and this probably reflect a form of wishful thinking. Even within his own lifetime Hohenheim was called the Martin Luther of medicine drawing parallels between his efforts to reform medicine and those of Luther to reform religion. This attributing of Luther’s birthday to Hohenheim has a certain ironic twist, as although the day of Luther’s birth is known fairly certainly there is a major dispute as to the year. This uncertainty led to a major dispute amongst astrologers in Luther’s lifetime who were attempting to determine, through his horoscope, Luther’s place in history, anti-Christ (Catholic astrologers) or saviour (protestant astrologers), a dispute famously documented by Aby Warburg in his ground breaking work on the history of astrology Heidnisch-antike Weissagung in Wort und Bild zu Luthers Zeiten. Interestingly Luther, who detested astrology, refused to comment on the dispute despite the fact that his closest friend and supporter Phillip Melanchthon, a passionate supporter of astrology, was intimately involved in it.


The problem of dates of birth of prominent and not so prominent Renaissance figures is not confined to Theophrastus of Hohenheim and Martin Luther. General registration of births did not exist and it is not unusual for a birth not to be registered but the baptism thus a least giving a fairly narrow range for the birth date as baptisms were usually performed as soon as possible after the birth due to the belief that unbaptised babies who died went to hell. Very often neither birth nor baptism records exist and the historian is forced to use other sources.


For prominent figures in the Renaissance a very useful source is horoscopes. Professional astrologers cast horoscopes of famous people in order to demonstrate that their biographies fulfil their birth horoscope forecasts in order to provide empirical proof of the scientific nature of astrology. Such horoscope collections are a valuable historical source for historians of the Early Modern Period, the most well known in English being John Aubrey’s Brief Lives. The Italian physician, mathematician, philosopher and astrologer Girolamo Cardano, who was one of those involved in the Luther horoscope dispute, actually establish his reputation as a scholar in Europe as the author of the first such horoscope collection to be printed and published; it being published in Nürnberg in 1545 by Johannes Petreius, who published Copernicus’ De revolutionibus two years earlier. Renaissance horoscopes are however somewhat unreliable as an exact source for birth dates, as it was an accepted practice amongst astrologers to rectify birth dates, that is to change them by one or two days, to make them better fit the biographies.


This lack of information on birthdays is exacerbated by the fact that people in this period did not celebrate their birthdays but their saints’ days, that is the day of the saint whose name they carried. This is of course not helpful in the case of Hohenheim as Theophrastus is not the name of a Christian saint but of the Greek philosopher who succeeded Aristotle as head of the Lyceum in Athens.


Filed under History of science, Renaissance Science

4 responses to “Not a birthday boy: some thoughts on Renaissance birth dates

  1. Pingback: Not a birthday boy: some thoughts on Renaissance birth dates | Whewell's Ghost

  2. Pingback: What’s in a name? | The Renaissance Mathematicus

  3. Pingback: What’s in a name? | Whewell's Ghost

  4. Thanks for the reminder (via twitter). I really appreciate your post and I have linked in a comment to our article from yesterday.
    Thanks and best regards,
    Harald (-> @yovisto)

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