A single book.
Somewhere around age 8 i stumbled across a copy of "The Complete Bladesmith" by Jim Hrisoulas. A tantalizing glimpse into the different techniques, tools, materials and information one would need to create not only beautiful, but functional swords and knives. I didn't know it then, but that book and it's information would stick with me.
Somewhere during college I discovered the Blacksmith's guild of the Potomac. On a whim I attended an open meeting, quickly entranced by hammers falling and blowers turning I could only watch as other members went about making leaves, hooks or whatever personal project they had going. An older gentleman named Tommy took notice of me, handed me a hammer and offered to teach me. He guided me through lighting a coal fire, how to swing, how to use tongs, and through making my first s hook. It wasn't a great s hook, uneven, a little goofy looking and slightly off, but damn if I wasn't proud of that little hook. It is holding up my apron in the shop now.
Somehow I stumbled onto a local bladesmith during a dinner out with some friends. Who took me over to meet his friends and I feel down the rabbit hole. It wasn't long until I joined the bladesmith forums, met Chris Price of the Tide water forge, and started attending my first hammer ins.