When Does a Riddle Become an Opening Line?

The first thing you look for, whether reading for flat-out enjoyment, scanning your own material for possible anomaly, or serving in the capacity of editor or teacher, both of which are paid positions, is the quality of puzzlement.  You want to know some of the "what" going on here.  You want to be driven to the involuntary click that means, Where am I being taken?

You also wish to know approximately how long you will be in this destination being extended to you.  How nice, how intense if you begin to fear that this project is one from which you will not return soon.  

Nicer still to suspect you are entering some life-altering experience, in its way a cosmic accident, yet still intriguing enough to cause hackles to stand on end, suggesting you are in a far-from-relaxed mood.

Since you prefer long odds to apparent certainty, you can't help wondering, when you're breathing life at your own creations, what the experience would be like were you to stumble upon not only a stunning opening line but as well a suitable follow-up as a way of convincing the potential reader that this venture is no accident; it is a valid report from a yearning, alert you, harpoon at the ready to impair the third sentence.

You have found such books, read them through again,in the process making discoveries of so ordinary a nature that  you begin to experience a glimmer of understanding about the way things in story seem to connect without any advance notice,

At the moment, you are preoccupied with an opening line you recall rejecting out of hand, the moment you saw it for the first time..  "Many years later, as he faced the firing squad, Colonel Aurielano Buendia was to remember that afternoon when his father took him to discover ice."

You came across the line not in the novel itself, but an ambitious list of the lines gifted men and women used to begin their novels, lines that transcended Once upon a time, lines that made you care inspire of your awareness that all successful fiction and a great many unsuccessful novels are crafted to rest on false pretenses.

The first line has to be a riddle, one that sneaks up on when you least expect it.