Inspiration is Rarity's Element, and Sweetie Belle her greatest achievement. But the filly has questions, ones that Rarity might not be able to answer on her own. What makes a pony? How can somepony know if they really are alive? Are they alive if they laugh and cry? Are they alive if they think, if they make mistakes and have ideas?
If Sweetie Belle is nothing more than a collection of wires, is she truly alive?