Ani cannot allow Okonkwo to corrupt his village with his angry actions and crimes, so the Earth Goddess Ani banishes Okonkwo to Mbanta, his mother's village, for seven years.
The last sentence about reliving the writers younger days as in memories
Seeds begin as a very small object or device, just like our courage. We only need a tiny little seed of courage for it to grow, and once you give that little courage it continues to grow.
Well there is the fact that he basically created a new religion just to devorce his wife becuase it was either that or he would murder them/behead them.