The poem has a religious tone because of the epigraph, Tenth day of fast, and the action of anointing, both significant religious rituals. Ironically, the fast has nothing to do with a sacred decision made by Soyinka but refers to his self-imposed fast in prison. Each stanza begins with a an anointing, first of the flesh, next of the voice and finally of the heart. His thoughts are "hallowed [this word gives holiness to his thoughts] in the lean oil of solitude." Perhaps he anoints himself with the "oil of solitude", or the act could be a blessing or prayer to remain sane and avoid drowning in the "oil".
In the first stanza he anoints his flesh, facing starvation, and the word "lean" repeats this notion of physical deprivation. The "oil of solitude" has such a suffocating tone, like being enveloped in a thick dark liquid. He wishes to illuminate something in the next lines saying, "I call you forth, all, upon/ Terraces of light." The "you" could have many meanings including his thoughts and fears, the men who have imprisoned him, the bats sitting on the wall above him, the bugs, or the sounds around him. Soyinka probably intended the word to have multiple interpretations, but clearly he wants "the dark to/ Withdraw" so he can see.
In the second stanza he anoints his voice, meaning he will not be silent whether his words are heard of "dissolve." He speaks of his voice being lost in "its lonely passage/ In your void"; again, the "your" seems unclear and could mean the empty cell or the hollow men who have imprisoned him. The next lines could be hopeful or desperate. The "Voices new/ Shall rouse the echoes" implies both that good voices will cry out like he has and that bad voices will keep the evil in motion. In any case, the "echoes" refer to sound being repeated in the "void" of the previous lines, and he does not hesitate to admit "Evil shall rise again" giving the poem and the struggle against evil a cyclical motion.
Finally, in a short four line stanza, he anoints his heart, perhaps in a last attempt to take courage from "within its flame," since he yearns for light. The lines make a twist and he lies in "spent ashes of your [probably the men who have imprisoned him] hate". The evil hatred has consumed him, and he remains nothing more than ashes with a heart and will. Close to his own death he commands, "Let evil die."
The first stanza ends with "Let the dark/ Withdraw", the second with "Evil shall arise" and the last with "Let evil die". The first two verbs again indicate a cycle of evil and darkness arising and withdrawing. The last line suggests an end to the cycle if evil could die.