What Diderot cares most about in literature and art is drama. He wanted to replace the neo-classical drama, which mainly served the feudal court in the 17th century, with the civic drama in line with bourgeois ideals, as a weapon of the anti-feudal struggle. With the rise of bourgeois power, classic tragedies and comedies and their traditional rules can no longer meet the requirements of the new era. This situation has long been prominent in more advanced bourgeois countries. For example, in Britain, the Elizabethan era marks the peak of English drama. Although the dramatists at that time still used the names of tragedy and comedy, they completely ignored the traditional rules of these two kinds of dramas, and their contents mainly reflected the bourgeois ideal of life and the realistic social contradictions, so they just brewed new wine from old bottles. Sometimes they find that old bottles can't hold new wine, so they simply create new operas. Shakespeare's tragic and joyful plays are an example. In Chapter 6, we have already mentioned the same reform made by Italian Guarini. The success of this mixed drama broke the superstition that the drama genre should be stereotyped by tradition. 17, 18 at the turn of the century, Britain developed a new kind of drama-sentimental drama, which further broke the framework of classical drama and wrote the daily life of ordinary people in daily language: emotions were mostly sentimental and slightly moral (the French took it as another name for "Le drame larmoyant"). It doesn't write about the upper class like tragedy, nor is it as arrogant as comedy. Its purpose has always been to carry forward the moral quality valued by the bourgeoisie, so it is also called "serious drama", which is actually the civic drama, that is, the originator of drama.

At the beginning of the Enlightenment, the influence of French neoclassical drama was still tenacious, and the general theorists did not evaluate this new type of drama highly, as can be seen from the nickname "Tears Drama". Voltaire's contempt for "the drama of tears" has already been mentioned above. Diderot is sensitive to new things, but has a shallow prejudice against neoclassicism. His attitude towards classical drama is dialectical: on the one hand, he affirmed the outstanding achievements of Gao Naiyi and Racine, on the other hand, he also opposed the affectation and discipline of classical drama. He thinks the new English drama is more in line with the requirements of the new era. At that time, the bourgeoisie often boasted about the moral quality of its own class in view of the decadent life of feudal nobles, in order to lower the status of the hostile class. This way of struggle was widely reflected in the new scripts and novels at that time. It is this tendency that attracted Diderot's stomach. He clearly pointed out that literature and art should have a moral effect on the audience. "When bad people see the bad things they have done, they should be filled with indignation and feel sympathy for the pain they have caused others." "After leaving the theater, the tendency to do bad things will decrease." Drama should carry forward virtue, which is "the love of order in the moral field". Therefore, drama should have realistic social content in subject matter. Secondly, Diderot thinks that if drama wants to produce moral effect, it must start with moving the audience's emotions, and in order to move the emotions, drama will produce illusions close to the real situation and convince the audience. He said, "the perfection of drama lies in the accurate imitation of the plot, which often makes the audience mistakenly think that they are there."

According to this requirement, French classical drama is too unnatural and calm to produce realistic hallucinations, arouse deep emotions and play its due educational role. Therefore, inspired by English sentimental drama, Diderot suggested creating a new drama between tragedy and comedy, which is more suitable for the requirements of the times. The total name is Les genres serieux, which is divided into Family Tragedy and Serious. In his talk with Doyle, he explained the ideal of his new play like this:

..... In drama, just like in nature, everything is interrelated. If we are exposed to the truth from one aspect, we will be exposed to the truth from many other aspects at the same time. Since prose is used, we can see the natural situation prohibited by general politeness on the stage (this is the enemy of genius and profound effect). I tirelessly shouted to the French: Be true! Be natural! To the ancients! Sophocles! Go to the picture of Philockler! The scene arranged by the poet for him is that he sleeps on the edge of a cave, covered with some rags, turns to the opposite side under severe pain, wails loudly and spits out some inaudible groans. The set is in the middle of nowhere, and he can perform without ostentation and extravagance. The clothes are true, the language is true and the plot is simple and natural. If this kind of scene is more touching than people wearing gorgeous clothes and artificial scenes, we can only blame our bad aesthetic taste.

Here, Diderot compares his ideal drama with neoclassical drama. As long as it is natural, he would rather be rough than hypocritical and decadent "civilization" He defined the nature of this new play as "citizen's and family's", with obvious political intention. Citizens are against nobles, and families are against the imperial court. He asked the drama to show the life of citizens and courts without nobles, and to write about the daily life of families. This requires drama to be close to reality and better serve the new class. Therefore, he urged writers to go deep into life, "live in the country, live in huts, visit their neighbors, and better yet, look at their beds, food, houses, clothes and so on." (1) the name was "empty valley footsteps".

When comparing serious drama with traditional drama, Diderot pointed out that tragedy is about "characters with personality", comedy is about "characters representing types" and serious drama is about "situations". This is a new point of view. Drama (as well as novels and narrative poems) usually pays attention to actions or plots like classical works, or to characters like modern works. Diderot put forward "situation" as the focus of the new drama, and clearly pointed out that "the characters depend on the situation", so the situation is more important than the characters.

Supplement:. (3) In combination with "situation", Diderot also put forward the concept of "relationship", explaining that "situation" is composed of "family relationship, professional relationship, friend-or-foe relationship and so on". There are two points worth noting here: first, he puts social content in the first place, and second, he has vaguely seen the close relationship between personality and environment. It is also novel to write a typical comedy about tragedy. This view conforms to Moliere's comedy, but it is not a dialectical view to oppose typicality and individuality.

Diderot also attached great importance to the plot handling in drama, but he still demanded that the plot be closely related to the situation. There are two points worth noting in this respect: the first point is his "contrast" theory. In the past, comedies often used the contrast of characters' personalities. For example, when an impatient and rude character appears, it is matched with a calm and gentle character as a contrast. Diderot opposes mechanical comparison, because it is not only monotonous, but also the theme is not clear, which makes the audience "don't know who they should be interested in." He believes that in real life, people are only "different" and not "diametrically opposed". Since the characters depend on the situation, a serious drama should adopt the contrast between the characters and the situation:

The situation should be strong, so that the situation conflicts with the characters and the interests of the characters conflict with each other. Don't let any one character try to realize his intention without conflicting with the intentions of other characters: let all the characters in the play care about one thing at the same time, but everyone has their own interests.

The real contrast is the contrast of personality and situation, and the contrast of different interests.

-On Drama Poetry, section 13

He went on to illustrate the contrast he asked for: "If you write about a miser falling in love, let him fall in love with a poor woman". This is the contrast between the rich and the poor. Two people have different backgrounds, different social status and different outlook on life, so they have different interests in the same thing, and the resulting situation is a dramatic situation. Thus, the "contrast" that Diderot said is actually contradiction and opposition, that is, conflict. In this way, the application of dialectical viewpoint to the development of drama plot exposes the bud of Hegel's "conflict" theory.

The second point is his view on the layout of the drama. On the one hand, he requires the plot to have realistic foundation and social content, on the other hand, he also emphasizes the role of creative imagination in handling the plot, which is also his dialectical point. He said:

Layout is to arrange an amazing history in the play according to the rules of drama genre; Tragedy can partially create this history, and comedians can create this history as a whole.

Supplement: This kind of creation should focus on showing the connection between events. There is an internal connection between a series of events in the real world, but because we have not fully understood it, this internal connection is often concealed by many accidental events, which makes it difficult to detect, so it shows some contingency. In drama, writers have the freedom to choose and arrange events, so they can put aside accidental things and highlight the internal relations of a series of events. Therefore, he believes that "compared with historians, dramatists show less authenticity and more realism". In Ritchie's Praise, he also said that "history is often just a bad novel, but a novel like you is a good history". This comparison between literary and artistic works and history is obviously influenced by Aristotle and is intended to distinguish between individual events that have happened and events that have seen regularity. Diderot called the former "truth" (truth of fact) and the latter "realism" (truth of reason). Drama and general literature and art are not history, but rational truth rather than factual truth. "Realism" is to show the internal relations of things as they should be. In this respect, literature and art are different from philosophy and science. It is not through abstract thinking, but through image thinking (that is, imagination). Diderot gave a very precise definition to the imagination of literature and art:

Starting from a hypothetical phenomenon, according to its necessary order in nature, we come up with a series of images, which is based on hypothetical reasoning, that is, imagination.

-On Drama Poetry, section 100

This definition is accurate, because it embodies the virtuality and logic of thinking in images, rather than absolutely opposing thinking in images and abstract thinking.

Regarding literature and art, from the objective basis, the most basic problem is the inevitability and universality of individual image (the unity of general and special, the true meaning of "typical"); In terms of subjective initiative, the most basic problem is the rationality or logic of thinking in images. Diderot not only grasped these two basic problems, but also pointed out the relationship between them: subject and object are unified in realizing "reality" and "imagination".