Baptisons-la infantia, ce qui ne se parle pas. Une enfance qui n'est pas un âge de la vie et qui ne se passe pas. Elle hante le discours. Celui-ci ne cesse pas de la mettre à l'écart. Mais il s'obstine, par là même, à la constituer, comme perdue. A son insu, il l'abrite donc. Elle est son reste. Si l'enfance demeure chez elle, ce n'est pas quoique mais parce qu'elle loge chez l'adulte. (9)

[Let us baptize that which does not speak infantia. A childhood that is not a phase of life and which does not pass. It haunts discourse. It {discourse} never ceases to set infancy apart, yet infancy persists, constituting it, as if lost. Unknowingly, then, {discourse} shelters infancy; infancy is its remainder. If infancy remains in its own place, it is not despite dwelling in the adult, but because of it.]

—Jean-François Lyotard, Preface, Lectures d'Enfance (Galilée, 1991; bootleg translation my own fault).

As soon as we attempt to talk about infancy we freeze it; we make it something that "loge chez l'adulte" and "qui ne se passe pas." Yet the fact that it passes is the defining condition of childhood. The state of infancy is all-confining, all-determining, inexorable, and is at the same time always slipping away, minute by minute: that's the point. It's temporary.

Temporariness is a difficult concept; therefore, so is childhood.