I think it was Rae Who said that back in the old days the pagans saw sacraficies as a way to thank the animal plant or whatever for giving its life up so they may live and to thanks the powers that be for makeing the animal or plant whatever.
I think it was in a Joseph Campbell book that I learned this. But, a native culture in South America played a game somewhat similar to our American football. At the end, they would make human sacrifices. Who did they sacrifice? You would think it would be the losers, but that's not right. They sacrificed leaders from the winning team. Basically, by doing this, they set that person on the level of a god. I'd have to look up all of the ins and outs of why they did this, since it's been awhile since I read about it. But, I found it to be interesting. Basically, it would have been insulting if they didn't sacrifice the winner.
So, in today's day and age we can say "Oooo. Sacrifice bad." But without knowing the entire cultural things going on when this was taking place, we can't really say.
Also, in today's society, I think it would be a good thing for more people to sacrifice their food if they are meat eaters. I believe the roots of sacrifice have to do with "making sacred." I would say most of us don't really do that anymore in regards to our plastic-wrapped meat. If we had to look our meal in the eye, and then kill it and dress it, we would have a whole lot more respect for it. I think Pagans are more mindful of this, but I'm sure we could all use some work.
But, even the "Do no harm" part of the read could be taken a thousand different ways...