This one by Russell Ackoff is more a list of lessons or insights than an actual essay but I decided to include it anyway, because some of them are quite good, especially around management, learning, how organizations should function, and affecting systems. As may be obvious from the highlights below, I also quite agree on his view of disciplines, and also love the addition of “understanding” in the first one.
[T]he hierarchy of mental content, which, in order of increasing value, are: data, information, knowledge, understanding, and wisdom. […]
[D]isciplines do not constitute different parts of reality; they are different aspects of reality, different points of view. Any part of reality can be viewed from any of these aspects. The whole can be understood only by viewing it from all the perspectives simultaneously. […]
Systems thinking not only erases the boundaries between the points of view that define the sciences and professions, it also erases the boundary between science and the humanities. Science, I believe, consists of the search for similarities among things that are apparently different; the humanities consist of the search for differences among things that are apparently similar. Science and the humanities are the head and tail of reality—viewable separately, but not separable.