"The Visual Display of Quantitative Information" by Edward R. Tufte

Rarely do I find a book that I would call beautiful, but this meets the criteria, both as a physically appealing book, apropos to the purpose of the book, and an informationally dense, and well presented one. A favorite quote of mine, from Zen and the Art of Motorcycle Maintenance, where the protagonist says; "I remember... remarking about the analytic craftsmanship displayed." This was my reaction to Tufte's book.

The book manages to decompose graphical presentation of data into categories other than the x- and y-axes, and instead talks about multifunctional elements and data density. The book reimagines the nature of numerical information using a graphical design perspective, with a healthy dose of common sense as to how graphs are used, and a veritable treasure trove of examples of both good and bad design.

This book, along with "How Buildings Learn," by Stewart Brand, is a rare example of a narrow focus with an incredibly broad appeal. This book is not for the narrow specialist in constructing the sometimes obscurely complex graphics displayed, but rather for anyone who is interested in the data presented to them, and certainly anyone who produces this data in any form.