What is the professor mainly discussing?

Good afternoon, class. Today, we’ll continue our discussion of modern American architects. Now, let’s review the three main elements that any architect must consider when designing a building.
      One of the elements is function. An architect must consider the function of a building, whether the design hinders or enhances the use of the building, whether the design allows for easy heating and cooling, plumbing, and electrical wiring.
      Appearance, the second element is appearance. Does the building fit in with its surroundings? Is it pleasing to look at or an eyesore? Its appearance is quite an important element.
      The last one is durability. An architect must consider a building’s durability, whether the materials will withstand wear from weather on the outside and from use on the inside.
      Now we’ll move on to discuss the architect. The man in this photograph is Frank Lloyd Wright. Frank Lloyd Wright has been called the greatest figure in modern American architecture because of his influence on function, appearance, and durability.
     I’ve placed several books on reserve in the library. Some of the books contain pictures and diagrams of Wright’s work, and there’s also an in-depth and...um...informative biography of Wright. The reserve material in the library is optional, but you may want to spend some time with it in order to have the best understanding possible of Frank Lloyd Wright and his work.