This ebook is part of a series of 5 books. This ebook is about certainty and uncertainty. Certainty is perfect knowledge that has total security from error, or the mental state of being without doubt. Uncertainty is the situation of unknown future. In the world we live in, some would say, the only thing that is certain is uncertainty. The quotations in this ebook have come from a myriad of sources. They have been collected over a period of many years. They have come from magazines, catalogs, newspapers, friends and relatives and many other sources.