What are some themes in Leandro Fernández de Moratín's writing?

Values of the Enlightenment
Moratín's work is an expression of Enlightenment ideas. Having traveled in France, he became a proponent of Enlightenment ideals and supported the French Revolution and Napoleon. His works endorse a reform of society along Enlightenment ideals. He also followed neoclassical models that were supported by Enlightenment thinkers. For example, his theatrical works always followed the classical idea of unity of time, place, and action, and his plays, like those of Ancient Greece, took place in the span of one day. He sought to rid Spanish plays of Baroque trappings and to use the theatre as a opportunity to influence societal reform. The Enlightenment sought to change society, and Moratín used satire to bring about reform.
Support for Women's Rights
His works criticized social practices of the time, including the practice in which young women were married to older men. His play El sí de las niñas (The Will of the Maidens) is a critique of the practice of arranged marriage. In this play, the young woman, Francisca, is allowed to break her marriage to the older man whom her mother wants her to marry, but she is at first prepared to go through with the match even though she loves another young man. Moratín criticizes the power that parents have over their children's marriages.
Valuing Reason Over Tradition
As a proponent of the Enlightenment, Moratín supported the idea of emphasizing reason over tradition. As Pao writes (see the source below), El sí de las niñas supports the use of rationality in marriage. Don Diego, the older man in the play, recognizes that his teenage bride should marry someone of her own age and that parents should consult with their children rather than order them to marry for money. Don Diego collects evidence about whom Francisca cares for, an endorsement of the Enlightenment idea of finding evidence rather than relying on the way things have always been done. The idea that reason, rather than customs, should govern people's actions was central to the Enlightenment.
Source:
Pao, Maria T. "Educating Paquita: The Maid and Moratin." Dieciocho 37.1. (Spring 2014).