The second edition of Universal Principles of Design contains 125 principles which apply across a wide range of aspects of design, from buildings to brochures and from aircraft to software. These are not all the principles of design which exist, nor are all of them even true (the authors point out where a principle is well-known, but little evidenced), but they are all challenging, significant (even if incorrect) and applicable in different disciplines. Whether you are a graphic designer, branding specialist, architect, interior designer, process manager or software engineer -- to name but a few -- this book helps apply principles from other trades to yours, and also helps to be confident that a great visual idea is not going to create problems when, for example, it's applied in another area.
From my point of view, this book is exceptionally useful for anyone in branding, because brands are all pervasive and impact on a wide range of applications and processes which might not be well understood by the team coming up with the brand. I suspect that the book is also very useful to people coming from the opposite direction, wondering how their architectural or process decisions will mesh with an organisation's overall brand.
It's also great fun, because the cross-connection of disciplines which are usually kept separate is itself a creative and refreshing experience.
I wish I had had this book ten years ago.