It was a good book to get familiar with exactly that, 20th century art. Still it's difficult art. It's less art as a medium to express reality, and more the object of reflection and the aim in itself. I still don't like the fact one needs to know the artist and his purposes to get a better grasp (or a grasp at all) of the art he's trying to make. Ortega y Gasset is right there, art in the 20th century became a bit elitist for one has to be informed. It's not that direct, the senses alone, -without some intellectual insight-, can't process it or simply enjoy it. But not all, some artists and pieces captivate from the get go, others, if one invests a little bit of time or makes a small effort, appear interesting and fully enjoyable.
All this said, yesterday I hang some art in my bedroom wall. I plan to cover it completely in time. For now, it has some relevant to me pictures. One I framed with two pages of this book, (yes, I cut the pages loosing the text behind.) This book had text on the left, one example of art on the right, for all the featured artists. My chosen paintings were "This is not a pipe" by my adored Magritte, and Mystery and Melancholy of a Street by Giorgio de Chirico. I placed them together in the same frame. They look gorgeous.
If one looks at the whole of the 20th century, one may gain a bit more understanding. Artists have been redefining art for quite a while, and their proposals all come to add more explored routes in art as a whole, and contribute another step to its history.