ABSTRACT
One of the main recurring themes of this book has been the idea that only a few simple types of differential equations can be solved explicitly in terms of known elementary functions. Some of these types are described in the first three chapters, and Chapter 5 provides a detailed account of second order linear equations whose solutions are expressible in terms of power series. However, many differential equations fall outside these categories, and nothing we have done so far suggests a procedure that might work in such cases.
