Epochful

First, an habitually good child sometimes has a saturnalia of defiance and disobedience; a series of insubordinate acts are suddenly committed which really mark the first sudden epochful and belated birth of the instinct of independence and self-regulation, on which his future manliness will depend.

This makes the end of the century epochful and momentous.

Kaes and Vulpius are in impressive agreement that the age of the later teens is epochful for the development of the middle layer, which then begins a new and prolonged period of growth.