Protect Your Macintosh, published by Peachpit Press in 1994, is Schneier's first book — a practical security guide for Macintosh computer users, written before applied-cryptography and before Schneier had developed the frameworks for which he would become known. It is primarily of biographical and historical interest: evidence of where Schneier began before his intellectual arc took its decisive shape.
The Early-Career Context
In 1994 Schneier was a security consultant working on practical computer security problems. The book addresses the concerns of that era: physical security of hardware, data backup and recovery, virus protection, and basic access controls. Cryptography appears but is not central — the technical cryptographic work that would produce applied-cryptography (also 1994) and eventually blowfish-algorithm and twofish-algorithm was proceeding in parallel.
The Macintosh focus reflects Schneier's consulting practice rather than a deep platform commitment. Peachpit Press was a leading publisher of practical Macintosh computing books in the early 1990s; a security guide for that audience was a natural commercial project for a working security consultant.
What It Is Not
Protect Your Macintosh does not contain the analytical frameworks that define Schneier's mature work. There is no security-theater argument, no threat-modeling methodology, no security-is-a-process formulation. These ideas emerged from the experience of the following decade. The book is a practitioner's guide in the traditional sense: here are the threats, here are the countermeasures, implement them.
Significance
The book's significance is mainly as a starting point. Schneier in 1994 was a competent security practitioner who could write clearly for non-specialist audiences — the same year he was working on applied-cryptography, a technically demanding book for a very different audience. The combination of practical accessibility and technical depth that characterizes his mature work is already present, even if the frameworks that would make that combination distinctive had not yet been developed. Protect Your Macintosh is the pre-history of the cryptography-era.