The Ten Cow-herding Pictures showing the upward steps of spiritual training is doubtless another such instance, more elaborate and systematized… I. Looking for the Cow: She has never gone astray, so what is the use of searching for her?
Suzuki presents the Ten Cow-herding Pictures as the canonical Zen allegory of spiritual development, in which the cow figures as the practitioner’s own buddha-nature, never truly absent yet perpetually sought.
, Essays in Zen Buddhism (First Series), 1949thesis