Zen master Dogen's expressions regarding how advanced his students were on the path included expressions such as "Leavers of Home," "Patch Robed Monks," and so on. It's not always obvious that these particular expressions aren't random, but they denote a specific hierarchy which can be directly related to the path of the Yogi.
Readers should relate this to the enneagram of form and non-form to understand some of the other Buddhist concepts that dovetail into this.
Leavers of Home aptly denotes the initial separation of the material from its origins in the absolute. On the level of the Buddhist path, it represents the aspirant who has separated himself from everything he knows in order to pursue his spiritual destiny. This aspirant has achieved a material manifestation of the initial wish to return to enlightenment.
Leavers of home are, furthermore outside. Although they have developed an aspiration, their work is essentially an external work
Patch Robed Monks are aspirants who have developed a wish— that is, desire— symbolized by the fact that they are now no longer just Leavers of Home, but monks. The external work has begun to clothe itself in an inner work, symbolized by the robe, but the work is still essentially external, visible, and is furthermore not well organized — it's in patches, bits and pieces, instead of made of a whole cloth.
The four levels that Zen monks most frequently speak of in terms of serious accomplishment are attaining the Flesh, Blood, Bones, and Marrow.
Flesh represents power, that is, the material ability to express the teaching. This requires what Gurdjieff called conscious labor to attain, which, in Zen, is composed of what is called "skillful means." The reason that skillful means are not considered to be sufficient is because they only represent the force necessary to complete the material side of the path.
This stage is the culmination of the external work, in which it becomes solid and real, and can potentially transition to a true inner work. It marks the final step on the path before the transition to an esoteric understanding.
Blood represents life force, which is the equivalent of Being or Agency. It marks the birth of a true inner work, on the level of the sun, the note sol. In Zen, the attainment of this level marks the ability of the aspirant to begin the real work of abandonment, or, an approach towards going beyond.
Abandoment, or the leaving behind of all things, is, in Buddhism, the shock represented by the force of what Gurdjieff called intentional suffering. There are specific esoteric reasons for understanding that these two actions are actually the same thing.
Bones represents purification. Once the aspirant has attained the Flesh and Blood, he must surrender them, stripping himself down to the pure white of the bones.
Marrow, the most essential stage on the path of Zen, represents the sweetness, the incomparable nutrition, that arrives with true wisdom.
As in the Sufi cosmology of Ibn al 'Arabi and the hierarchic path of the Yogi, Zen follows the same inexorable requirements for inner development, using what initially appears to be obscure allegorical language. The language, however, clearly indicates the same hierarchy we see in the other systems, with the same inner obstacles and challenges that need to be assimilated and overcome.