Paradise of Fools
The Hindus, Mahometans, Scandinavians, and Roman Catholics have devised a place between Paradise and “Purgatory” to get rid of a theological difficulty. If there is no sin without intention, then infants and idiots cannot commit sin, and if they die cannot be consigned to the purgatory of evil-doers; but, not being believers or good-doers, they cannot be placed with the saints. The Roman Catholics place them in the Paradise of Infants and the Paradise of Fools.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894