Desiderius Erasmus Roterodamus (also Desiderius Erasmus of Rotterdam) (October 27, probably 1466 – July 12, 1536) was a Dutch humanist and theologian.
His best-known work, Praise of Folly (Dutch: Lof der Zotheid), was dedicated to his friend Sir Thomas More. In 1536 he wrote De puritate ecclesiae christianae in which he tried to reconcile the different parties. Many of his writings appeal to a wide audience and deal with matters of general human interest; he seems to have regarded these as trifling, a leisure activity. His more serious writings begin early with the Enchiridion Militis Christiani, the "Manual (or Dagger) of the Christian Gentleman" (1503). In this short work, Erasmus outlines the views of the normal Christian life which he was to spend the rest of his days in elaborating. The chief evil of the day, he says, is formalism, a respect for traditions without consideration for the true teaching of Christ. The remedy is for every man to ask himself at each point: what is the essential thing? and to do this without fear. Forms may hide or quench the spirit. In his examination of the dangers of formalism, Erasmus discusses monasticism, saint-worship, war, the spirit of class and the foibles of "society", but the Enchiridion is more like a sermon than a satire. Its companion piece, the Institutio Principis Christiani (Basel, 1516), was written as advice to the young king Charles of Spain, later Charles V, Holy Roman Emperor. Erasmus applies the general principles of honour and sincerity to the special functions of the Prince, whom he represents throughout as the servant of the people.
As a result of his reformatory activities, Erasmus found himself at odds with both the great parties. His last years were embittered by controversies with men toward whom he was sympathetic. Notable among these was Ulrich von Hutten, a brilliant, but erratic genius, who had thrown himself into the Lutheran cause and had declared that Erasmus, if he had a spark of honesty, would do the same. In his reply, Spongia adversus aspergines Hutteni (1523), Erasmus displays his skill in semantics. He accuses Hutten of having misinterpreted his utterances about reform and reiterates his determination never to take sides.
The most important work of this last period is the Ecclesiastes or "Gospel Preacher" (Basel, 1535), in which he brings out the function of preaching as the most important office of the Christian priest, a Protestant emphasis. His little tract of 1533, "Preparation for Death", in which the emphasis throughout is on the importance of a good life as the essential condition of a happy death, shows another tendency.