**Claude Hardy**'s father was Sébastien Hardy, seigneur of Estour and of Tabaize. Sébastien had been born in Paris in 1564 but had studied in Le Mans where he became a tax collector. He married Marie Belot Despontis in Paris around 1596 and their son Claude, one of their seven children, was born in Le Mans. The date of his birth is uncertain, some experts giving 1598 and others giving 1604. Sébastien Hardy was an educated man who used his skill in languages to made translations from Spanish and Italian. The Hardy family moved to Paris soon after Claude was born where Sébastien was named as a Conseiller at the court. In 1604 the family were living in rue Quinquempoix, in the parish of St Jacques de la Boucherie but by 1610 they had moved to a home in rue St Honoré, in the parish of St Germain de l'Auxerrois.

We know nothing of Claude's upbringing other than the locations of the homes in which he lived. However, in 1613 he published a translation of a work by Erasmus under the title *De la civilité morale des enfants*. This work, dedicated to the twelve year old King Louis XIII, was:-

This, of course, suggests that Claude Hardy was indeed born in 1604 (being nine years old in 1613), but this seems somewhat at odds with when his father was known to be in Le Mans. It is possible, of course, that Hardy did translate the work when nine years old but it was only published some six years later. Although it might seem impossible for so young a child to translate from Latin to French, we do know that Hardy had the reputation for being a remarkable linguist with knowledge of thirty-six languages. His friends claimed that some of these languages took him no more than one day of study to master them. Even if these claims are somewhat exaggerated, nevertheless it is clear that Hardy, taking after his father, had a remarkable ability to learn languages. In 1614 he published another translation, this time the work of the poet Michel Verin who died in Florence in 1487 at the age of 19. The poetry was translated from Latin to French by Hardy and published as a prose work... composed in Latin by Erasmus; translated into French by Claude Hardy, Parisian, aged nine years.

*Les Distique Moraux de Michel Verin*. This time the book claimed to be:-

Perhaps given the young age of the translator, it is not too surprising that the translation has been described as "lively, sometimes obscure, and full of dubious and antiquated expressions." In the Preface, Hardy pays a fine tribute to his father.... translated into French by Claude Hardy, Parisian, aged eleven years.

Nothing of Hardy's education in Paris is known and the first information about him after 1614 is not until 1622 when records show that Claude Hardy married Perrette Presche in Paris. These records give his date of birth as 1604, making him eighteen years old when he married. Nothing is known about Perrette Presche. In 1625 we know for certain that Claude Hardy was a practising lawyer in Paris. Hardy, in his capacity as a lawyer, worked for the Parliament in Paris from 1625. A year later he was certainly attached to the court of justice in Paris as a counsellor. In 1625 he published another work, this time *Euclidis Data, & Marini Philosophi in Data Euclidis commentarius graece & latine*. He edited the Greek edition of Euclid and provided a Latin translation of the work and the commentary by Marin Mersenne. He became involved with a group of mathematicians working in Paris at this time, in particular becoming a friend of Claude Mydorge. He was in Mydorge's home when he was introduced to René Descartes who was a friend of Mydorge. This was the beginning of a close friendship between Hardy and Descartes during which they exchanged views on all the scientific and philosophical issues of the day. Hardy's great skill in languages made him extremely useful to Descartes and to other scholars who often turned to him for help with translations, particularly from Arabic. In a letter which Descartes wrote to Mersenne on 20 November 1629 he says:-

A translation into French of Viète's book on algebra, originally written in Latin, appeared around 1630 with Antoine Vasset as the translator. It is believed that "Antoine Vasset" was a pseudonym for Claude Hardy. In 1630, under his own name, Hardy publishedAnd I assure you, that if you give Mr Hardy a good dictionary in Chinese, or any other language whatsoever, and a book written in the same language, he will undertake to make sense of it.

*Examen*and in 1638 he published

*Refutation*. These works dealt with the problem of the duplication of the cube and in them Hardy pointed out a fallacy which had arisen regarding this problem [1]:-

Hardy took part in the meetings Mersenne organised with Roberval, Gassendi, Descartes and others such as Étienne Pascal and later his young son Blaise Pascal. In 1637 Mersenne gave Descartes a copy of Fermat'sSeveral writers of the seventeenth century suggested methods for the duplication of the cube, including Viète, Descartes, Fermat, and Newton. Among the less well-known persons who also occupied themselves with this problem was Paul Yvon, lord of Laleu, who claimed that he had found the construction of the two mean proportionals, required in solving the problem. In addition to Mydorge and J de Beaugrand, Hardy exposed the fallacy of Yvon's construction ....

*De Maximis et Minimis et de Tangentibus*to review. Descartes wrote a strong criticism of Fermat's work which he gave to Mersenne with instructions to forward his review to Fermat. Mersenne also let Roberval and Étienne Pascal, both friends of Fermat, see Descartes' critical attack. Descartes wrote to Mersenne making sure that others, particularly his friend Hardy, be given details of the controversy. An argument followed in which Hardy took Descartes' side, as did Mydorge and Desargues, while Fermat was supported by Roberval and Étienne Pascal. Of course, Fermat's methods as given in

*De Maximis et Minimis et de Tangentibus*are perfectly correct but he had not stated his innovative results rigorously enough to satisfy his opponents. One must also realise that Descartes believed that only with his methods could really innovative mathematical ideas be discovered so he was set against ideas from anyone who had not followed his way of thinking. The important point to make here is the high value which Descartes placed on Hardy's opinions and support.

Finally, we know Hardy undertook chemistry experiments with Annibal Barlet, a physician who taught alchemy in Paris, and with Pierre Borel, before he became physician to Louis XIV in 1654. After the death of Descartes in 1650, information about Hardy vanishes and we know nothing about the last 25 years of his life.

**Article by:** *J J O'Connor* and *E F Robertson*