puerile

1850, Thomas De Quincey, French and English Manners (originally published in Hogg's Instructor The French have been notorious through generations for their puerile affectation of Roman forms, models, and historic precedents.

Today we should welcome, and even study, every serious attempt to envisage the future of our race, not merely to grasp the very diverse and often tragic possibilities that confront us, but also that we may familiarize ourselves with the certainty that many of our cherished ideals would seem puerile to more developed minds.