He walked around the inside of the arc, passing out a small gemstone to each pony. "Magic is power.  It is part of the world yet apart from the world.  It springs up from all around us, and within.  All that lives carries a spark of magic, and everything that has a will, that has emotion, can call it forth.  There are different kinds of magic, and different forms it can be shaped into.  These gems carry an enchantment, a portion of magic bound to the gems that will do something specific.  In this case, they will take in ambient magic and glow."