Here are some farther evidences of the greater mind, given by Lombroso (After Death, What?, 320 f.): 

It is well known that in his dreams Goethe solved many weighty scientific problems and put into words many most beautiful verses.  So also La Fontaine (The Fable of Pleasures) and Coleridge and Voltaire.  Bernard Palissy had in a dream the inspiration for one of his most beautiful ceramic pieces....

Holde composed while in a dream La Phantasie, which reflects in its harmony its origin; and Nodier created Lydia, and at the same time a whole theory on the future of dreaming.  Condillac in dream finished a lecture interrupted the evening before.  Kruger, Corda, and Maignan solved in dreams mathematical problems and theorems.  Robert Louis Stevenson, in his Chapters on Dreams, confesses that portions of his most original novels were composed in the dreaming state.  Tartini had while dreaming one of his most portentous musical inspirations.  He saw a spectral form approaching him.  It is Beelzebub in person.  He holds a magic violin in his hands, and the sonata begins.  It is a divine adagio, melancholy-sweet, a lament, a dizzy succession of rapid and intense notes.  Tartini rouses himself, leaps out of bed, seizes his violin, and reproduces all that he had heard played in his sleep.  He names it the Sonata del Diavolo,...

Giovanni Dupre got in a dream the conception of his very beautiful Pieta.  One sultry summer day Dupre was lying on a divan thinking hard on what kind of pose he should choose for the Christ.  He fell asleep, and in dream he saw the entire group at last complete, with Christ in the very pose he had been aspiring to conceive, but which his mind had not succeeded in completely realizing.

It is a quite frequent experience that a person perplexed by a problem at night finds it solved on waking in the morning.  Efforts to remember, which are unsuccessful before going to sleep, on waking are often found accomplished.

A dream is a work of genius, and in many respects, perhaps most, especially in vividness of imagination, the best example we have.  It is the most spontaneous, constructed with the least effort from fewest materials, the least restrained, and often immeasurably surpassing all works of waking genius in the same department.  A genius gets a trifling hint, and being inspired by the gods (anthropomorphic for:  flowed in upon by the cosmic soul?) builds out of the hint a poem or a drama or a symphony.  You and I build dreams surpassing the poem or the drama or the symphony, but our friends Dryasdust and Myopia inquire into our experiences, and sometimes find a little hint on which a dream was built, and then all dreams are demonstrated things unworthy of serious consideration.  Is it not a more rational view that the fact that the soul can in the dream state elaborate so much from so little, indicates it to be then already in a life which has no limits?