According to Berger et al., how do traditional oil paintings perpetuate the wealth and power of the ruling class?

Oil paintings are able to make objects desirable to the touch of an owner. In oil paintings, the subjects appear real and tangible, which creates a desire to own and obtain the materials that the painting depicts. Also, formal portraits are made to present the subject as powerful and ruling over other people of lower stature. The combination of the tangibility and presentation of subjects bends the ways of seeing to promote the ruling class.