Put things on the shelf, come back and revisit them later. “I used to tell my children, when they would ask questions to which I could give no answer, “There are some things you just have to put on the shelf for a while. Later you take them down and reexamine them. Sometimes then the question can be answered by new information or understanding that has come your way. Sometimes the question no longer holds any interest. Sometimes it must be put back on the shelf for another day. In the meantime, you just bide your time and go ahead on the basis of what you do know.”