"You will note that none of them are presently glowing.  That is because unlike the magelight gems in your homes, the form is weak; these gather next to nothing from the air and earth around them.  But you can change this."  He makes his way back to the front of the room, crossing his arms before him.  "All of you carry magic.  In fact, you ponies have more innate magic than most of my former minions. I believe you express it naturally in many ways, such as in your marks, but I suspect you can learn to bring it forth."