The Alchemist is a satirical comedy. Like other satirists, Jonson hopes to expose and mock the vices, follies, and errors of humanity and, more specifically, of 17th-century London. In the Prologue, Jonson clarifies the aims and methods of satire, both generally and in this play:
Fortune, that favours fools, these two short hours,
We wish away, both for your sakes and ours,
Judging spectators; and desire, in place,
To the author justice, to ourselves but grace.
Our scene is London, 'cause we would make known,
No country's mirth is better than our own:
No clime breeds better matter for your whore,
Bawd, squire, impostor, many persons more,
Whose manners, now call'd humours, feed the stage;
And which have still been subject for the rage
Or spleen of comic writers. Though this pen
Did never aim to grieve, but better men.
First, Jonson attempts to banish “Fortune”—who “favours fools”—from the stage, suggesting that he intends instead to punish the foolishness of his characters. The play is set in London, he claims, because no other “clime” or location provides such ample material for satire. In the early 17th century, satirists often portrayed London, a bustling urban center, as a city abounding with criminal and sinful behavior, and Jonson here indexes the various “underworld” figures (“whore, Bawd, squire, imposter”) who populate The Alchemist. These figures, drawn from the criminal underclass of London, have “been subject for the rage / Or spleen of comic writers,” though Jonson insists that his goal in portraying sinful and criminal behavior is not to “grieve” the audience but rather to “better” them. In the Prologue, then, Jonson presents his play as a satirical work that uses humor and characters with exaggerated traits to serve a moral lesson.