Please excuse my weak knowledge in this area. I find the cooking laws of Shabbat quite confusing and I'd like to get a simplified understanding of it, if possible.
Apparently, pouring hot water from a kli rishon (first vessel) into a kli sheini (second vessel) suffices for it not to be considered "cooking".
As I understand, "cooking" is defined as "yad soledet bo" - i.e., if the temperature is so hot that your hand would flinch from the heat, it is considered cooking.
My question on all this. I think most people would agree that even by the time you pour that hot water into the 2nd vessel, it is still yad soledet bo. So, why does the kli sheini technique work?
Also, It seems that the vessel you pour the liquid into should be the biggest factor in temperature change. If one poured the liquid into an ice cold glass beer mug, it would cool much more quickly than if it were poured into a hot aluminum cup that was left on the blech.
If you would, feel free to edit the question if I got any of these concepts way off. My main question is regarding the idea of the kli sheini.
I request that your answer be in "layman's terms". Of course, sourcing is a big help in case I want to research further, but, please try to offer a "simplified" English source. I've looked at the "big" 39 Melachot book in English, and I'm still not quite understanding this.