Herbert Read in his Introduction to this work says that it constitutes " the most profound and illuminating statement of the aesthetic basis of the modern movement in art ever made by a practicing artist" I do not have the professional knowledge or aesthetic training to quarrel with Read. I can only give my personal impression of Klee's treatise which was given at the opening of an exhibition in Jena in 1924. I understand that Klee is in the Treatise arguing against the view that the criterion for judging the work of the artist is its being an accurate copy of nature. Klee puts the emphasis on the organic shaping power of the creative process , and gives examples of how this works. The text contains sketches by Klee illustrative of the process. My suspicion is that this focus on the 'organic ' the growing and developing element is what makes Klee so congenial to Herbert Read whose Theory of Art focuses on this concept.
However I personally could not really understand the process as Klee describes it in this work. Read says the book is cryptic and aphoristic. I did not find it aphoristic but I did find it cryptic and more.
Perhaps here however it is wiser to "Trust the Artist and not the Reader" as my own understanding in these matters is limited.
One point. The work is very short, the illustrations 'pleasant' if not perhaps as profound as Klee maintains them to be.
Other readers truly have to judge for themselves.

Just a quick note on the number of pages. It only contains 56 pages of text amd images, not the over 150 pages as provided in the item description.

As for the content 5 out of 5.

This slim volume is the text of a lecture Klee delivered in 1924 on the occasion of the opening of a museum exhibit of modern art. It is both an educational lecture on color and form and an explanation of modern art that largely escapes being a defense. Klee's discourse is not simply an historical piece. It is as valid today as it was when he delivered it seventy-two years ago. Klee was Kandinsky's neighbor during the years they both taught at the Bauhaus. They shared more than the basement that connected their duplex apartments; they shared a belief in art as a spiritual pursuit.