Although there is no question that the symbolism was fundamentally related to rain, it is evidently true that Cocijo was a god of the lightening that the Zapotecs saw as the operative force in splitting the clouds to release the needed rain. That concept of an operative force, with its clear implications of creative power, may explain the close relationship between Cocijo and the earthly rulers of the Zapotec people. The power of these rulers wielded was derived from the gods, and upon their death, they “became gods” through whose mediation mortal men could approach the essence of divinity.
Such a concept of rulership no doubt accounts for the great numbers of urns depicting human beings wearing headdresses displaying the mask of Cocijo, a way of displaying a mask in ritual regalia.
-P. Markman & R. Markman, Masks of the Spirit: Image and Metaphor in Mesoamerica, pg 33.