The mandala has been defined (by Toga no Shozui) as "a symmetrically arranged symbolic diagram used in Hinduism and esoteric Buddhism to express fundamental religious doctrine for the purposes of ritual and medication."
There are other definitions. That of Elizabeth ten Grotenhuis, currently teaching at both Boston and Harvard universities, is that "the mandala, a kind of cosmic ground plan or map, lays out a sacred territory or realm in microcosm, showing the relations among the various powers active in that realm and offering devotees a sacred precinct where enlightenment takes place."
Each culture has elaborated the mandala form to suit its own individual needs. Those of Tibet are different from those of India, which are, in turn, very different from those of China. Those of Japan, which ten Grotenhuis studies in this interesting monograph, are more different yet. These are a number of distinctions in the Japanese form and it is these with which the author deals.