No, don't bother offering an explanation. I figured out where they come from. But for years, I was amazed that this 70-lb. book dense with information would magically appear on my doorstep. I mean, the typing alone must have taken thousands upon thousands of man-hours, let alone the numberless crappy drawings of mufflers and whatnot. And it was free! What off-kilter philanthropist was responsible for this? You can't blame me for perceiving an aura of miraculosity about the whole enterprise. The truth, once I discovered it, was like a layer of soot deposited over the landscape, which really happened on a regular basis during my chilehood in Eastern Ohio, where they burned nothing but bituminous coal, and where the governors have all looked like Mr. Potato Head and have all had names like "Taft", which is exactly the sound I make when a little bug flies into my mouth.