A magic spell is a social pact where we offer up our agency (the "sacrifice") by conditioning our response to a ritual (often involving the speaking of specific words, ie, the "casting" of a spell) so that that ritual can be weaponized by another person (the "witch") when the conditioned response is triggered within a social group and the effect of its empathic response to played out.

The reason why magic requires a sacrifice is that words have power only because we offer up our power to them.

The fact that people are getting so easily triggered by so many words nowadays makes me think Magic is still growing strong despite the rise of Science.