Nicholas "The Pest" Barnaud achieved much renown in his life and is perhaps best known among alchemical and theological circles as a mystery and heretic. On the side, he was apparently also a physician. Very little is known about him except for his works and some few pseudonyms and a rough timeframe of when he lived. There is not even a sketch of him to show what he looked like. He was born at Crest in Dauphiné. Through his life, Nicholas visited Spain in 1559, was at Paris in 1572, and later fled to Geneva, where he attempted to assist the Protestants as a diplomatic emissary. Still later, he settled in France to live out the rest of his life writing and editing very controversial texts.

Barnaud was definitely of anti-Catholic sentiments, his views being more in line with Faustus Socinus, and he rejected the the Holy Trinity of The Church. This does not, however, appear to affect his works, as many of them, especially The Book of Lambspring involve Catholic themes, and he was also one of the first (and last) to attack Mary, Queen of Scots after her marriage to Lord Darnley in 1565, and even suggest her execution in his work Dialogues (1574). Though there is some debate over whether or not this is actually his work, since the compiler is unknown, it is generally attributed to him.

Barnaud's most controversial work is considered to be the Huguenot political polemic, Le Réveille-Matin des Francais et de leurs voisins (prétendus) (1573), under the name of Eusèbe Philadelphe. In this work, he insists on the marriage of priests and the abolition of tithes, pursues the theme of a grand Huguenot alliance with the House of Guise to overthrow the Valois Dynasty, justifies tyrannicide and the right of resistance to oppression, and outlines a novel form of political control for society with clear republican implications.

Barnaud is also tied to the origins of Rosicrucianism and it is an alchemical tradition that he was a key precursor of the Rosicrucian Brotherhood. His son, Govaert Basson, published Robert Fludd's very first Rosicrucian pamphlets. According to J.S. Semler's Unparteiische Samlungen zur historie der Rosenkreuzer (1788) alleges that in 1591 Barnaud, who is known to have travelled in France and Holland that year, founded an alchemical society implying that Barnaud was associated with "a great college of the fraternity of the Rosicrucians". That Barnaud may have organized some alchemical sect is quite possible; in 1597 he produced his Commentariolum in Aenigmaticum quoddam Epitaphium, which contained the "alchemical Mass" originally written by the Hungarian, Nicholas Melchior.

Though we may never know the full story of Nicholas Barnaud, he no doubt had quite an impact on the religious and alchemical societies of the Renaissance.