Living where I do, I have found that my car's horn is extremely important. When I'm driving at night and a deer runs out in front of me, the first thing I do is hit the horn; the second thing I do is hit the brakes. For the last couple of weeks, my horn has been out of commission. I have encountered several deer on the roads around my neighborhood, but I have been without a way of getting their attention.
That "deer-in-the-headlights" look you may have heard about is REAL. A deer will stand smack-dab in the middle of my lane and stare at my car--without moving--until it hears the horn. Then the ears come forward, the tail flicks, and it continues to stand there until it has evaluated the situation, at which point it either decides I am no threat, or it decides it should probably move.
Mind you, the car is barreling down on the dumb animal at 40-50 mph, even with the brakes applied and the horn blaring. Hmmmmm, the deer seems to think casually. Perhaps I should take that sound as a warning. Maybe it's a ploy to get me to move away from the salt I'm licking off the pavement. (All of this is occurring within a fraction of a second.) It's getting closer. It does appear to be a bit of a danger, so I guess I'll move a little bit and see if that scares it off. It takes two steps--directly toward me!--and stomps its front feet to warn me that it has staked a claim on that spot in the road.
I now begin to pump the brakes and repeatedly hit the horn to let it know I'm actually there and not just a figment of its imagination. It appears to get the point and moves off, though I have to make sure and watch both sides of the road because there are usually at least two of them, and the partner(s) will invariably follow the first one's lead. Again, I hit the horn and come to a stop, luckily without making contact with any other member of the herd. I wait for my adrenaline rush to pass, then I move on. Without the horn, I may not be so lucky. The deer--and my car--could be history.
OK, here's the reason for all of that: the deer is analogous with my hook line. Without a hook line to get my reader's attention, my story could end up as venison stew, I'd rather have the horn and make my intentions known. In the same manner, a reader will have to make the move to buy it or simply stand there and become an insignificant grease spot on the pavement, so to speak.
See what a hook line can do?