The noble nobleman Liseo, accompanied by the servant Turin, comes from the province to Madrid: Liceo expects a joyful event – a wedding. His future wife Phineus – the daughter of the famous and respected in the capital of the noble Octavio. Octavio has another daughter – Nisa, who is famous in the area for her extraordinary intelligence and education. Phineas also knows how, to his chagrin, Liseo learns by talking in a tavern, a fool, whose ignorance and the absence of any manner of manner have become a talk in the streets in Madrid. At the same time, Liceo becomes aware that Phineas is given a large dowry, which she inherited from an eccentric uncle, who was extremely fond of this niece. There is no dowry behind Nisa. Heard a few discourages Liceu, but he can not retreat and hurries to Madrid – make up his own opinion about the bride and,
Meanwhile, in the house of Octavio, the groom was already waiting. The head of the family complains to his friend Miseno how much trouble both his daughters give him, each in his own way: one depresses his father with excessive stupidity, the other with excessive scholarship, which Octavio, an old-schooled man, seems completely unnecessary in a woman. At the same time, the rich dowry of Phineas draws suitors to her, while Nisa’s hands, despite all her talents and beauty, are not being sought. In fact, in Nisa, passionately in love with Laurencio, a poor nobleman, fond of writing poems. Passion for literature and brought together young people: Nisa pays Laurencio complete reciprocity. But if Nisa worships before Heliodorus, Virgil, is read by ancient Greek poetry, then for her sister Phineas even to learn the alphabet is an impossible task. The literacy teacher, exhausted with her, is losing patience and refuses to teach anything to this girl, convinced that “the creator of the brain has not given her a grain of it.” Young people come to Nisa to hear her opinion on the newly composed sonnet, and Phineas revives only when her faithful servant Clara, quite fit for her mind and development, tells in detail how their cat sucked.
But although Laurencio has a sincere feeling for Nisa and considers her perfect, he, being a man of a noble family, but poor, recognizes the need to be guided in his behavior by reason and not by feeling, and leaving Nisus begins to take care of Phineas. Having taken such a decision, he immediately goes on the offensive, but his elegant, full of elegant comparisons syllable not only does not conquer Phineas, he does not understand it, because this girl only perceives all words in a literal sense. The first attempts do not bring any result, which causes the young man to regret the decision: Phinea never thought about what love is, and, for the first time hearing this word, even intends to find out its meaning in the father. Frightened Laurencio barely has time to stop her. The situation is no better with Pedro, the servant of Laurencio, who decided to take care of Clara.
Finally comes the long-awaited Liceo, who, seeing both sisters nearby, to Phineas’ displeasure, begins to lavish praises on Nisa’s beauty, Phineas, on her acquaintance with her future husband, shows herself on the worst side: her stupidity, misunderstanding and ignorance of the simplest things are so obvious that even the father feels awkward for her. Liseo, immediately realizing what a misfortune can come upon him in the event of marriage, immediately abandons the intention to link his fate with such a fool. Nisa’s beauty also contributes to this decision.
A month passes. Liseo lives in the house of Octavio as the groom of Finee, but the talk about the wedding subsided. Liseo spends time, caring for Nisa and trying to achieve her love, but little succeeds in this: arrogant girl is cold to him and continues to love Laurencio. The same, on the contrary, was much more successful, gradually winning the love of Phineas. And this feeling completely transformed the recent fool: woke up dozing in her mind and innate subtlety of nature. Sometimes Phineas is still rude, but you can not call her a fool. Nisa is tormented by jealousy and reproaches Laurencio for infidelity, he rejects such accusations and assures Nisa of his love. The witness of their explanation becomes Liseo: finding Neus alone with Laurencio, he calls the opponent to a duel. But, appearing... at the place of the fight,
Concealed by jealousy, Nisa angrily reproaches her sister that she encroaches on her Laurencio, and demands the return of her unfaithful lover, leaving Liseo for herself. However, Phineas already had time to fall in love with Laurencio and suffered severely, seeing him next to her sister. She tells about her tormenting Laurencio unconcerningly, and he assures us that only one means can help: it is necessary, with the witnesses – and they are around – to declare their consent to become Laurencio’s lawful wife. And in the presence of the friends of the young man – Duardo and Feniso – Phineas immediately joyfully follows this advice. Meanwhile, after an explanation with Laurencio, Liceaulto, with even greater zeal, tries to win Nisa’s favor and openly confesses to her that he does not intend to marry Finee at all. But even after such a recognition, Nisus continues to indignantly reject his claims. Phineas are changing day by day. She herself does not recognize herself and explains her transformation with love: she began to feel thinner, she became curious. The change was noticed by everyone around: in the city they only say that the new Finee. Charter unsuccessfully to seek the love of Nisa, Liseo decides to return to Fine, since Nisa openly admitted to him that he loves Laurencio, with whom, in her opinion, no one can be compared neither intellect nor education nor valor.
On the decision of Liceu immediately – through the servant – becomes known to Laurencio. This news discourages him: he managed to sincerely love Phineas, and the idea of the possibility of losing her makes the young man suffer. Phineas finds a way out: she is going to pretend to be the old fool Phineey, over which everyone mocked, so that Liceo again refused it. She is quite successful in this, and she easily deceives Liseo, Nisa, and her father. But jealous doubts still do not leave Nisa, and she asks her father to forbid Laurencio to visit their house, which he enjoys doing: he is irritated by the young man’s passion for writing poems. Against the expectation, Laurencio does not take offense and expresses his readiness to leave the house of Octavio, but on condition that this house with him will be abandoned and his betrothed. He explains to the astonished Octavio that for two months now, As they are engaged to Phineas, and asks his friends to confirm this. Enraged Octavio refuses to acknowledge this engagement, and then Phineas devises to hide Laurencio in the attic. Octavia, in order to avoid any other surprises, tells Finia to hide from her eyes, while at least one other man remains in the house. As a refuge, the girl chooses an attic, to which Octavio immediately agrees.
He then speaks in the most decisive way with Liceu, insisting on an early wedding with Phineas: the city already has gossips because the young man lives in the house for the third month, not being the husband of any of the daughters of the master. Liseo refuses to marry Finee and asks Octavio to give him to Nisa. But her hand is already promised to Duardo, the son of Miseno, the friend of Octavio, and the angry father gives Liceo the time until the next day to decide whether he will marry Finee or leave their home forever. Immediately there is a new challenger at the hands of Phineas, and she has to pretend again to be a fool and, referring to her father’s will, to go to the attic.
Meanwhile Selya, Nisa’s servant, traces Clara in the kitchen, collecting a large amount of food in the basket, and, following her to the attic, sees through the gap Phineas, Clara and two men. Octavio rushes there to find out who has disgraced his house. Laurencio says in his defense that he was in the attic with his wife, and Phineas – that she was carrying out her father’s order. Octavio is forced to accept the choice of “clever dumb”, as he calls his daughter, against whose wishes he does not want to go, and give her hand to Laurencio. Taking the appropriate minute, Liceo once again asks Nisa’s hands – and receives the consent of his father. Do not remain forgotten and the servants: Pedro, servant Laurencio, gets married to Clara, and Turin, the servant of Liseu, – Selju, This, to everyone’s pleasure, and the play ends.