The Four Steps to the Epiphany

Steve Blank

Long before "lean startup" became a buzzword, this book laid out the actual discipline behind it: get out of the building, talk to real customers, and validate before you scale.

A foundational text that introduced "Customer Development" as a parallel process to product development, arguing that startups need to systematically discover and validate their customers before scaling, since no business plan survives first contact with real customers.