First mentioned in Book 4: Neverseen, the Inception Date is when the unborn elf's heart starts beating, signaling the start of life. In the Lost Cities, elves use an Inception Certificate instead of a birth certificate and measure age from the inception date, not the birth date. The Inception Date is about nine months before the actual birth of an elf. The inception can be detected when the mother's belly button pops out and turns pink. Sophie had been counting her age wrong her entire time in the Lost Cities, up until in Neverseen, when she had to fill out an enrollment form for Exillium.