On departing this earth, not only must we leave behind our material possessions; all the other kinds of things that we have received from people or books are also erased unless we have made them our own experience at a very deep level. And when we come back again in our next incarnation, we must painstakingly relearn everything.
Just because someone can talk or write about all kinds of subjects does not mean that they really know them; they will have to start over again from the beginning.
And look, people get married and have children, and many of them are as helpless and lost as if they were facing these situations for the first time.
Yet they must have been in similar circumstances any number of times in previous incarnations! But since they have never truly sought to understand their role and their responsibilities as husband or wife or parent, it is always as though they were dealing with it for the first time, so they make silly mistakes and they suffer.