"Scientific Advertising" by Claude C. Hopkins. This book is turning 100 years old next year, but what I loved about it is that because it predates the Internet

"Scientific Advertising" by Claude C. Hopkins. This book is turning 100 years old next year, but what I loved about it is that because it predates the Internet (and even TV and the mass proliferation of radio), it doesn't get bogged down in specifics. But, the principles laid out in this book almost entirely apply to online marketing. So when I read this book, everything clicked. The closest I can compare it to is when you first learn multiple programming languages and develop an abstract understanding of the concepts. Once you have that abstraction, you can generally pick up any language pretty quickly. It's mostly just semantics. Similar to this book's impact on my understanding of digital marketing. With the basic concepts of scientific advertising under my belt, I can pretty confidently hop into any platform and learn the syntax, as it's the same ideas, simply reimplemented with better tech.