. the mandala as metropolis 743
sions. To what extent did Kūkai invent Japanese Shingon, and to what
extent did later Japanese visitors to the Tang keep quiet about their
possibly heterodox understanding while acquiring new materials? Or
did they perhaps teach Kūkai’s synthesis to their Chinese hosts, but we
have not yet discovered evidence of this? Investigating such a possible
feedback loop of influence would require the concerted efforts and
combined expertise of scholars in both Chinese and Japanese esoteric
texts and images.
Second, Chinese and Japanese masters claim that their esoteric
methods protect the state and liken their efficacy to city walls. This
metaphorical link seems to be well supported by the visual materi-
als, and future research will hopefully uncover more explicit textual
links between the mandala and the metropolis. Until that time, and
until we learn precisely by whom and how the mandalas were first
designed, the art historical methods of visual analogy and chronologi-
cal development of forms (even those as monumental as imperial city
plans) seem to be our best tools for discerning the latent organizing
principles behind these most intriguing images.