"Entropy theory is indeed a first attempt to deal with global form; but it has not been dealing with structure. All it says is that a large sum of elements may have properties not found in a smaller sample of them"

Rudolf Arnheim's quote is describing the idea of entropy, which is a measure of condition in a system. Entropy theory is an attempt to describe the habits of large systems, such as the universe, by looking at the habits of its private components. Nevertheless, Arnheim is suggesting that entropy theory does not consider the structure of the system, which is very important for understanding how the system works. He is stating that although entropy theory can inform us about the total habits of a system, it does not tell us about the individual elements that make up the system and how they communicate with each other. This suggests that entropy theory is not enough to completely comprehend the habits of a complicated system. Therefore, Arnheim is recommending that other theories ought to be utilized to much better comprehend the structure of a system and how its private elements engage with each other.