The “theory of human vision” of the title is essentially a theory of processing digital information, where processing includes both the storage and the transmission of information. All digital information can be represented as strings of bits. Therefore, it can be represented as matrices (not necessarily rectangular) of bits. Therefore, it can be represented by one-liners in APL. The author points out that the propagation of information, in many cases, can be represented by the ≠\ operator of APL. Thus, a theory of information storage and transmission can be represented in APL.

Until now, I have no argument with the author. But he seems to feel that APL is the best way to express such a theory. I do not agree. APL is not a natural language with which vast numbers of human beings feel comfortable. Thus his audience is limited to those who are willing to read a philosophical treatise written in APL.

Among the examples Langlet gives are the Braille alphabet, the structure and chemistry of the retina, chaotic fractals, and DNA. Thus his audience is further limited to those who are interested in a treatise on these topics. His presentation and figures are sufficiently clear for even a nonexpert to follow. His style is exuberant, both about his theory and about APL, which is perfectly reasonable for an oral presentation at an APL conference.