However, I think it's fairly safe to say that in addition to the physical reality we are all participants in, there are also our individual private realities which arise from our own biological processes filtering or interpreting the shared physical reality. In these private realities our thoughts literally dictate the structure of what we perceive, in tandem with language and personal experience. And in the end we tend to place more value, trust, and confidence in our private reality than the cold-hard "here and now."
This is where the idea of karma comes into play most directly; that the energies we extend toward life and its other participants will in some way or another find us again, whether directly or indirectly. Action > reaction... only, the reaction may not be linear or predictable because the action probably wasn't as well, much as most of our private realities are rarely either linear or predictable for that matter.
When we turn down the babble [via meditation] of the brain filtering and interpreting 'hard' external reality, we often see how irrational much of our life really is, and that that's understandable given that we're all running around listening to our private realities, assuming that others are experiencing the exact same thing as you, and not trying to integrate any of it with the larger external Reality.
This is one of the keys to understanding the Buddhist concept of non-attachment to things - the less attached we are, the less of that energy we're extending trying to hold on to something that's absolutely incapable of being held onto (such as life and its pleasures, or people, or ideas that make us feel better but do not stand up to logical scrutiny, or anything really - even Buddhism!) - the less we surround ourselves with mental trinkets & curios that we feel belong to us, the less subject to laws of karmic reaction we become. It's as simple as that.
Does this mean we'll ever completely rid ourselves of attachments, completely transcend that desire to own/have something last forever? Not likely. It's more like spiritual harm reduction, though - the healthier you make yourself, the better your life becomes.
Now I can see that this might've opened another can of worms - namely, this Buddhist idea of attachments being counterproductive... but that's another discussion for another time.
