This early work on mathematics is both expensive and hard to find in its first edition. It contains details on the principles of abstract spaces, linear operations, vector valued functions and many other aspects of functional analysis. This is a fascinating work and is thoroughly recommended for anyone interested in mathematics. Many of the earliest books, particularly those dating back to the 1900s and before, are now extremely scarce. We are republishing these classic works in affordable, high quality, modern editions, using the original text and artwork.