There appears to be no truth whatever in the theory that dreams come as omens or warnings, for they are purely accidental. Neither is there apparently any truth in the belief that dreams come by opposites, that they are the manifestation of some invisible agency, or that there is anything supernatural, uncanny or mysterious about them.
To maintain that one can foretell future events, or read past events, from dreams, is absurd. Nearly every person dreams each night, and particularly during the moments when losing consciousness and the moments when awakening, since imperfect sleep then obtains; and, it would be strange indeed if, during one or more of these occasions, we did not by chance dream of something which afterwards actually happens.
All bodily derangements that interrupt healthy sleep, such as irritation of the digestive organs, and even over-exertion, worry, and undue excitement, will produce dreams, and it is therefore fairly obvious that, since we know the cause of dreams, their effects and results, there is nothing marvellous, unnatural, wonderful, extraordinary or supernatural in dreams.
Until the past few hundred years, the cause of dreams was not understood. Aristotle believes the cause of dreams to be common sense, but placed in the fancy. Avicen thought it to be an ultimate intelligence moving the moon in the midst of that light with which the fancies of men are illuminated while they sleep. Averroes, an Arabian physician, ascribed it to the imagination. Democritus referred the cause of them to little images, or representations, separated from the things themselves. Plato placed it among the specific and concrete notions of the soul. Albertus attributed dreams to superior influences, which continually flow from the sky, through many specific channels.
In order to disdelusionize, it will be necessary to get a clear understanding of the nature of the mind and of its workings. "When the mind turns its view inward upon itself," says John Locke, "and contemplates its own actions, thinking is the first that occurs. In it, the mind observes a great variety of modifications, and from them receives distinct ideas. Thus the perception, which actually accompanies, and is annexed to any impression on the body, made by an external object, being distinct from all other modifications of thinking, furnishes the mind with a distinct idea which we call sensation; which is, as it were, the actual entrance of an idea into the understanding by the senses.
"The same idea, when it occurs again without the operation of the like object on the external sensory, is remembrance; if it be sought after by the mind, and with pain and endeavor found, and brought again in view, it is recollection; if it be held there long under consideration, it is contemplation; when ideas float in our mind without any recollection or regard of the understanding, it is that which the French call reverie; our language has scarce a word for it. When the ideas that offer themselves (for, as I have observed, while we are awake, there will always be a train of ideas succeeding one another in our minds) are taken notice of, and, as it were, registered in the memory, it is attention; when the mind, with great earnestness, and of choice, fixes its view on any idea, considers it on all sides, and will not be called off by the ordinary solicitations of other ideas, it is what we call intention or study. Sleep without dreaming is rest from all these; and dreaming itself, is the having of ideas (while the outward senses are stopped, so that they receive not outward objects with their usual quickness) in the mind, not suggested by any external objects, or known occasion, nor under any choice or conduct of the understanding at all, and whether that which we call ecstasy, be not dreaming with the eyes open, I leave to be examined."
We often converse with a dead or absent friend, in our dreams, without remembering that the grave or the ocean is between us. We float, like a feather, or fly like a bird, upon the wind, one moment in New York, and the next in Melbourne, without reflecting that the laws of nature are suspended, or inquiring how the scene could have been so suddenly shifted. We accommodate ourselves to every event, however romantic, impossible, unreasonable, extravagant and absurd.
We also dream awake, which dreams may be called reveries or waking-dreams, and they are sometimes as chimerical, and impossible to be realized, as our sleep dreams. Many fabulous stories of apparitions, magic, and apparent miracles, owe their origin to some form of dream.