In "In the Navel of the Soul," contrast is not a mere ornament but the organising principle of the whole poem. The poet sets two ways of knowing side by side, the intuitive world of tradition against the measured world of modern science, and lets each throw the other into sharp relief. The opening allusion to Pascal's idea that the heart has reasons the mind cannot grasp already fixes this pattern of opposition between instinct and intellect, and the rest of the poem plays it out through the single situation of how a pregnancy is detected.
Contrast of two cultures and two methods. The central opposition is between the traditional birth attendants and the modern medical experts. The traditional midwives are dignified as "midwives of the spirit," women who, laying a finger upon the navel, can "feel a foetal throb" and so sense the hidden presence of new life. Against them stand the "experts" who trust only their tests and instruments. By placing the simple, felt knowledge of the one beside the clinical procedure of the other, the poet dramatises the clash between an African, intuitive way of understanding and an imported, scientific one.
Contrast heightened by diction and irony. The poet's word choice keeps the two worlds distinct: warm, human terms like "feel" and "throb" for the midwives, cold, technical terms for the "experts" and their tests. The irony sharpens the contrast further. The scientific urine test records a negative result while the midwives, with nothing but their fingers on the navel, correctly detect the foetus. The "quizzical glare" of the experts, meant to look superior, instead exposes their confusion; those who seem authoritative are shown to be the ones who are wrong. Thus the expected order is reversed, and the tradition the modern world would dismiss is vindicated.
Effect and meaning. Through this sustained contrast the poet defends indigenous knowledge and quietly rebukes the assumption that Western science is always superior. The opposition of the two methods carries the poem's deeper argument: that the African way of understanding life should not be stifled or looked down upon. Contrast therefore does the poem's real work, turning a small domestic scene into a statement about the value and endurance of traditional wisdom in the face of modern science.