Robert Bringhurst, The Solid Form of Language.
Bringhurst writes elegantly about scripts, alphabets, and written language, and how written language lives in a world slightly differently than the oral language from which it springs. He shows how different languages evolve different scripts according to their different characters, and how scripts can be uniquely suited to a particular language--and how other scripts can be so incredibly mutable as to allow many, many different languages to use the same script.

This book is slight, but elegant. It illustrates a number of scripts in principle and in use, and while a quick read is an eminently enjoyable little book.

It's also quite poetic. Here's the beginning:

"Drop a word in the ocean of meaning and concentric ripples form. To define a single word means to try to catch those ripples. No one's hands are fast enough. Now drop two or three words in at once. Interference patterns form, reinforcing one another here and canceling each other there. To catch the meaning of the words is not to catch the ripples that they cause; it is to catch the interaction of those ripples. This is what it means to listen; this is what it means to read. It is incredibly complex, yet humans do it every day, and very often laugh and weep at the same time. Writing, by comparison, seems altogether simple, at least until you try.
Writing is the solid form of language, the precipitate. ..." (Bringhurst 9)