Okri's work is particularly difficult to categorise. Although it has been widely categorised as post-modern, some scholars have noted that the seeming realism with which he depicts the spirit-world challenges this categorisation. If Okri does attribute reality to a spiritual world, it is claimed, then his "allegiances are not postmodern he still believes that there is something ahistorical or transcendental conferring legitimacy on some, and not other, truth-claims." Alternative characterisations of Okri's work suggest an allegiance to Yoruba folklore, New Ageism, spiritual realism, magical realism, visionary materialism, and existentialism.