Quiet, uninterrupted thought, necessary not only in imaginative work, but in creative effort has a trick of gradually slipping into reverie, thence into day-dreaming, whereupon materialism loses patience. Physiology is even prone to classify reverie and its gradation into day-dreaming as symptomatic of nervous disorder. With a suspicious smile the physician questions the patient as to the depth and character of the hallucination. In fact it is almost as dangerous to admit to day-dreaming as it is endangering to the reputation to repeat the night dreams in the hearing of a skilled analyst. While the nocturnal dream may bring to light hitherto unsuspected depths of depravity in the moral character, the day-dream bears scarcely less humiliating scientific possibilities in its revelation of the mentality.

A few of earth's great ones, from the pinnacles of fame, have been unafraid of their reveries, illusions and day-dreams. One of these was Socrates, who through the portals of immortality has nevertheless been called to account by Dr. Greisinger with the up-to-date and unpleasantly flippant suggestion that the historic daemon, the philosopher's guide and counsellor, was none other than "an incipient, auditory hallucination symptomatic of an incipient mental hallucination."

Precisely what terms the learned Dr. Greisinger would use to define the ailment of Sprenger, the inventor of the automatic brake, who found the secret of its mechanism in a dream, we do not presume to guess, any more than we could judge the mental status of Professor Lamberton, the great mathematician who worked for weeks upon the solution of a problem whose answer finally came to him in a dream.

The poet Sotithey attributes John Bunyan's "Pilgrim's Progress" to the inspiration of the following dream:

"About this time the state of happiness of the people at Bedford was thus in a kind of vision presented to me - I saw as if they were on the sunny side of some high mountain there refreshing themselves with the pleasant beams of the sun, while I was shivering and shrinking in the cold, afflicted with frost, snow and dark clouds; methought also betwixt me and these I saw a wall that did compass about this mountain. Now through this wall my soul did greatly desire to pass; concluding that, if I could, I would there also comfort myself with the heat of their sun.

"About this wall I bethought myself to go again and again, still prying as I went to see if I could discover way or passage by which I might enter therein; but none could I find for some time. At last I saw as if it were a narrow gap, a little doorway in the wall through which I attempted to pass. Now the passage being very straight and narrow, I made many offers to get in but all in vain - At last, with great striving, methought I at first did get my head in; and after that, by a sidelong striving, my shoulders and my whole body; then I was exceedingly glad and went and sat down in the midst of them, and so was comforted with the light of their sun.

"Now this mountain and wall was thus made out to me: the mountain signified the church of the living God; the sun that shone thereon shining of His merciful face on them that were therein; the wall I thought was the wall that did make separation between the Christians and Christ, who is the way to God the Father. But as the passage was wonderfully narrow, even so narrow that I could not but with great difficulty enter in thereat, it shewed me that none could enter life but those that were in downright earnest and left the wicked world behind them; for there was only room for body and soul and sin. This resemblance abode in my soul many days." - Autobiography of John Bunyan.

Tasso, the poet, contended that he was guided by a daemon who frequently appeared to his dreams, and, being a poet, it is safe to say that he was held as mad. Many things, we are told, that Tasso would never otherwise have known were conveyed to him by this familiar spirit.

Lord Byron received several suggestions from ghosts which appeared to him in his reveries, and Alfred de Musset was so obsessed by his day-dreams and imaginings that he found difficulty in distinguishing the real world from his world of shadows and it became necessary to call upon his brother to help him to discriminate.

Milton is said to have received inspiration from a vision, a muse who dictated to him his "unpremeditated song."

Sir Walter Scott also was visited by visions, one of which he recognized as Lord Byron after that erratic young bard had met his untimely death.

One of Goethe's favorite occupations was watching for ocular spectra, and he could at will transform these day-dreams into definite sensations; he frequently made different varieties of flowers arise from one bouquet and rain in an endless shower of blossoms. It is even said that he once saw an exact counterpart of himself coming across the fields in full daylight.

Pope, the poet, was likewise subject to day-dreams or visions; and Berlioz's music roused visions like those of De Quincey in Heine's soul.

While Mozart was composing his "Requiem," the vision of a melancholy man in black arose and urged the completion of the composition with as little delay as need be. When the requiem was finished the vision ceased to appear. Mozart died shortly afterwards.

Dr. Johnson frequently heard his absent mother calling to him, and Descartes says that after a long confinement he was constantly followed by an invisible person adjuring him to pursue his search for truth.

Rousseau, De Quincey, Charles Lamb and numerous writers of fact as well as those who weave fiction have had daydreams that have aided in their work. To Charles Dickens in particular they came with peculiar force and color, moving through his actual life with the verve of flesh and blood personalities. The death of Dora in "David Copperfield" and the end of little Nell's brief life, the Dickens biographers tell us, filled the kindly heart of the novelist with very real sorrow. To quote Dickens's own words: "There are manifold problems in literature except by the suggestion that the mind is at times the instrument played upon by the fingers of some unseen force, and when I sit down to write my book, some beneficent power shows it all to me and tempts me to be interested - and I don't invent - really do not - but see it - and write it down."