The speaker asserts that the arts reveal society's hidden ideas and impulses. While this assertion has merit, I think it unfairly generalizes about art. Consider two particular art forms: architecture and painting. In more important architecture one consistently sees a refection of society's ideas and urges. However, in more important paintings of the most recent century one sees instead the artists' personal and idiosyncratic visions of an aesthetic ideal.
Turning first to public architecture, one sees in ancient and Renaissance forms an impulse to transcend the human condition. Clearly, the most important architecture of these periods was built to honor deities and to propel humans into the afterlife. Consider, for example, the ancient pyramids and the great cathedrals of Europe, which rise upward toward the stars and heavens. During the Medieval period the most important architectural form was the castle, which reflected an overriding concern for military security and brute strength during a time of comparative anarchy. During the 20th Century it was first the steel-forged art deco forms and then the sky-scraping office building that dominated public architecture. These forms reflect modern, more mundane concerns for industrial and technological progress.
Turning next to important paintings and painters, it seems to me that the art of previous centuries reflected the attitudes and ideas of the prevailing culture to a far greater extent than today's art. The cynosures of the Medieval and Renaissance artists, for instance, were certain Christian themes--the Trinity, virgin birth of Christ, the Resurrection, and so forth with which the society at large was also preoccupied. Later, during the 18th and 19th Centuries, an emerging genteel class saw itself reflected in the bourgeois themes of impressionists such as Renoir and Monet.
But in the most recent century the picture has been much different. Consider three of the 20th Century's most influential painters: Picasso, Dali and Pollock. Picasso's style underwent a series of radical changes throughout his career. Was the reason for Picasso's diverse "periods" a quick series of radical changes in society's ideas and impulses, or perhaps a reflection of society's hidden impulse for constant change? Or did Picasso's varied styles merely reflect the complex psychological profile of one eccentric artist? Dali is known for his surrealistic images; but do these images reveal some kind of existential angst on a societal level, or just the odd aesthetic vision of one man? Pollock's penchant was for dripping paint on the floor in order to create abstract images that would have the sort of visceral impact he was after. In fact, Pollock turned to this technique only after he tried but failed as a conventional painter, using brush and easel. So are Pollock's striking abstract murals a reflection of some mid-20th Century societal impulse, or merely the result of one struggling artist stumbling onto something he was good at? In all three cases, it seems that the art reflected the artist but not the society.
In sum, in the art of painting one can observe a shift from styles and themes reflecting broad societal impulses to a more recent concern for expressing personal impulses and creative urges. In contrast, the more public art form of architecture has always mirrored society's ideas and impulses, and probably always will--because architecture is so much more public than the art of painting.