One thing leads to another?

Reader question: What does the expression "one thing leads to another" mean exactly?

My comments:

Cause and effect.

Farfetched? Maybe, maybe not – to me, the expression signifies the fact that you're responsible for what happens to you. Let me make up an example for you. You're walking, say, down the street at Wangfujing, the shopping district. That place is thronged with people even in the slowest business day and inevitably you bump another pedestrian on the shoulder. He stops. You stop. He casts you a look, you know, that look. You look back. He makes a remark. You make a remark. One word leads to another and before you know, you're immersed in a major quarrel in a busy street, drawing a crowd of onlookers of your own...

You see, every step on the way, you've allowed the series of events to happen, one after another. That's why everything that happens to you is your own doing.

Everything terrible that is.

I'm joking, of course. I'm not being serious, but you get the picture, along with the phrase. The Chinese equivalent to "one thing leads to another" will be the equally plain and beautiful "一来二去".

Anyways, here are a few real examples:

 I only asked him in for a coffee, but one thing led to another and we ended up in bed together (thefreedictionary.com).
 Goals and Goal Setting (slooy.com).
Personally I've always drifted along, unconsciously using the "one thing leads to another" approach. I thought goal setting was for executive types. I have to admit I didn't understand how to set a goal. I've never really given it any thought. I certainly didn't know how to consciously get to one even if I had one in mind. That's not to say I've never achieved success through my life because I have. I acquired entry into one of the most challenging to get into university courses at THE best university in my country. I had the job of my choice, ready to walk into months before my graduation. I can give you many more examples but the point I'm making here is I've managed to achieve many wonderful things with little thought of how to achieve them. Now I'm filled with excitement and anticipation that I can actually create a most amazing future through the methods of goal setting that I'm beginning to learn. I'm also excited as I feel the instruction I'm receiving is second to none. The methods used are totally in harmony with who I am. They are easy to incorporate into my day-to-day busy schedule and they make total sense. I'm stunned that I've done so well with out them!

"Our French friends seem to have touched the spot this time. No doubt it's just as they say. She knocked at the door – surprise visit, I guess, for he kept his life in water-tight compartments. He let her in – couldn't keep her in the street. She told him how she had traced him, reproached him, one thing led to another, and then with that dagger so handy the end soon came. It wasn't all done in an instant, though, for these chairs were all swept over yonder, and he had one in his hand as if he had tried to hold her off with it. We've got it all clear as if we had seen it" (The Return of Sherlock Holmes, Arthur Conan Doyle).