First, let's quickly tell people what are the "Five Ranks". One of the root teachers of Soto Zen in China, Dongshan/Tozan, is said to have formulated five ways or directions in which the "relative/form" and the "absolute/emptiness" fit together, and play with/in/as each other (and eachother) ... usually rendered as something like ...
the relative within the absolute
the absolute within the relative
coming from the absolute
arrival at mutual integration
Taigen Dan Leighton makes this point, citing another scholar:
It is clear that later writers added all kinds of interpretations, poetic embellishments and esoteric meanings and diagrams to the 5 Ranks. It got quite complicated, almost like Jews interpreting Kabbalah or fortune tellers reading the I-Ching.
Most discussions of Dongshan focus on this five ranks teaching.[iii] One modern Chinese commentator, just before presenting an extensive discussion of the five ranks and Dongshan's related teachings, ironically states, "This doctrine and others like it are not of central importance in the teachings of Tung-shan's school [Tung-shan is the older Wade-Giles transliteration for Dongshan]. They are merely expedient means or pedagogical schemata for the guidance of the less intelligent students. It is regrettable that historians of Ch'an have a tendency to treat these incidents as essentials and to ignore the true essentials altogether."[iv]
It is actually my understanding that Dogen was --not-- a fan of the "Five Ranks" or any too pat and clean model of things. Taigen again comments ...
James Mitchell writes in Soto Zen Ancestors in China (he uses the Chinese term "principle" referring to the "absolute" and "phenomena" to mean "the relative"):
Dôgen clearly criticizes such analysis, saying, "If buddha-dharma had been transmitted merely through the investigation of differentiation and oneness, how could it have reached this day?" and "Do not mistakenly say that Dongshan's buddha-dharma is the five ranks of oneness and differentiation."[xlv] It is intriguing that Dôgen titles his essay "Spring and Autumn," the seasons when heat or cold are least intense. And yet, in his introduction Dôgen extols Dongshan's summit of cold or heat, and says that "Cold is the vital eye of the ancestor school. Heat is the warm skin and flesh of my late master."[xlvi] This concerns direct experience, beyond systematic formulations such as the five ranks.
to the various statements regarding emptiness, Buddha-nature and thusness, which
conform in every respect to the commonly accepted teachings of all the chan schools,
Dongshan also develops the teaching of the Five Ranks, represented in the Sung histories as
the characterizing philosophical doctrine of the emergent Cao-Dong School. The Five Ranks
of Dongshan are a set of five modes in which apparent or phenomenal reality interacts with
ultimate or absolute reality. In traditional Buddhist terms, the teaching demonstrates five
possibilities for the construction of form and emptiness. In traditional Chinese terms, the
Five Ranks show the interactive relations of li (principle) and shi (phenomena). The recorded
teachings of Caoshan Benji likewise indicate the importance of the Five Ranks in the early
years of Cao-Dong School. They contain extensive elaboration, through the systematic use
of metaphor and symbol, of Dongshan's original theory.
Its [the Five Rank's] popularity and employment as a teaching device seems to have varied
enormously from generation to generation – Dogen Zenji seems to have been little
impressed with it – but it is reasonable to say that it has always had at the very least a
background presence throughout the later history of Cao-Dong School. Indeed the Sungperiod
chan histories agree in emphasizing Dongshan's Five Ranks as the original teaching
of the school, which alone probably would have precluded the possibility of its complete
The point here is not that Dogen rejected insight into the "relative" and "absolute" .... because no Mahayana Buddhist teacher would do so. It is fundamental. What is more, so many of Dogen's writings express this dance of the "relative and absolute". I believe that the first lines of Genjo Koan, as the essay points out, do express this dance of relative and absolute as discussed in the essay you link to ...
As all things are buddha-dharma, there are delusion, realization, practice, birth and death, buddhas and sentient beings. As myriad things are without an abiding self, there is no delusion, no realization, no buddha, no sentient being, no birth and death. The buddha way, in essence, is leaping clear of abundance and lack; thus there are birth and death, delusion and realization, sentient beings and buddhas. Yet in attachment blossoms fall, and in aversion weeds spread.
It is simply that Dogen was not a fan of formulas or models to express this living dance of "relative" and "absolute". I do not think he was a big fan of the "Five Ranks" as a good way to capture this vibrant vibrant interpenetrating wholeness flowing dance. The essay you posted says the following, and I do not think it particularly wrong. It says ...
... but I would say that Dogen's vision of the intricated intimate dance of form-emptiness was much more than 5 or 50 or 500000 or 1/5th of a Rank. I am also not particularly a fan of the rest of the essay, which seems convoluted and loses me. Statements like this in the essay seem a bit like psycho-babble ...
Dōgen outwardly rejected the formulaic and structured approach of
the Five Ranks as a teaching method. However, he covertly inserted them into many areas of his
writings, especially the Shobogenzo, because he understood their value in undermining deep-seated
misconceptions even though he considered systematic and academic forms not to be consistent with
traditional teachings of the Buddhadharma.
[scared] Loses me.
The Universal becomes powerful enough to
permit a practitioner to use its positive and thoroughgoing vision to directly perceive the nonfabricated
voice of nature. Forgetting the self of accumulated habits and conditioned states permits
the voice to resound clearly. The strong Universal perspective allows a vigorous and close
examination of conditioned states without getting trapped by them. Their harmful effects are not
quite put to rest as yet. Nevertheless, they are for the most part recognized for what they are and
appropriately dealt with.
I hope that helps.