That is because the work of saving mankind cannot be finished straight away during one period, or in one location, but gradually becomes deeper according to man’s level of development at different times and places.
Hiyo ni kwa sababu kazi ya kumwokoa mwanadamu haiwezi kumalizika mara moja katika kipindi kimoja, au katika eneo moja, lakini hatua kwa hatua inakuwa ya kina zaidi kulingana na kiwango cha maendeleo ya mwanadamu katika nyakati na mahali tofauti.