What are the major themes in the play The Imaginary Invalid?

The seventeenth century, when The Imaginary Invalid was written, was a fascinating age, in which a deeply religious culture intersected with the birth of the scientific revolution. The tension generated between these two often conflicting worldviews is illustrated by Molière using the theme of obscurantism. This simply means the deliberate withholding of information with the purpose of keeping people in a state of ignorance. Devotees of the scientific revolution often accused the authorities—especially the Catholic Church—of peddling false notions such as geocentrism, the discredited theory that the sun revolves around the earth rather than the other way round.
Yet in reality the picture was a good deal more complicated than this. Molière shows us, that despite the scientific revolution and its extraordinary advances, there was often a fine line between science and outright quackery. Monsieur Diafoirus and his son Thomas are physicians, yet they reject current developments in science such as Harvey's discovery of how blood circulates round the body, in favor of more ancient treatments. Though supposedly men of science, Monsieur Diafoirus and Thomas are thoroughgoing obscurantists, dispensing quack remedies to their patients without shame. Precisely the same charge often leveled at the time against the Catholic Church can thus be used against these two charlatans. Moreover, Diafoirus, both father and son, realize that the newfangled science undermines their claims to expertise, damaging both their reputations and their earning power.

The play's theme include the following:
First, Moliere satirizes or makes fun of the medical profession. Moliere gets laughs from the incompetence and greed of his doctor characters and critiques the incompetency of the medical profession of his time. Doctors like Monsieur Purgon and Monsieur Fleurant are selfish, pretentious in their use of Latin, and, beneath all their posturing, profoundly ignorant. The play also questions whether it is even possible to understand the human body well enough to reliably cure illness, since mortals are destined to die.
Second, Moliere pits young love and its pursuit of pleasure against the money concerns and pragmatism of the older generation. Angelique and Cleante yearn to marry but are up against Argan's total control of his daughter's fortune and his desire to save money.
Third, Moliere critiques and makes fun of middle-class society. In this play, he portrays it as petty, money-hungry, immoral, and incompetent.