E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Unlawful pleasure, illicit love, vain hopes. Thus, in Romeo and Juliet, the Nurse says to Romeo, If ye should lead her [Juliet] into a fools paradise, it were a gross . behaviour. The old schoolmen said there were three places where persons not good enough for paradise were admitted: (1) The limbus patrum, for those good men who had died before the death of the Redeemer; (2) The limbus infantum or paradise of unbaptised infants; and (3) The limbus fatuorum or paradise of idiots and others who were non compos mentis. (See LIMBO.)