“In his home, where he was born, there is a lantern. We all have one. We must revisit it every so often and replenish our energies with it. If we don’t, we die. Simples!” he said, his head low, sniffling into the tissue that Dusty had given him.

"Simples"?

I don't really know, sorry. Is this a typo or a way of speaking?