The influences of the day's occurrences, and the thoughts which have occupied the mind during the day, have been said to give a corresponding tone and coloring to our dreams at night. Thus the lover dreams of his mistress; the miser of his gold; the merchant of his speculations; the man of science of his discoveries. The poets of all ages and nations adopt this view. Virgil describes Dido forsaken by Æneas, wandering alone on a desert shore in pursuit of the Tyrians. Milton represents Eve relating to Adam the dreams which were very naturally the repetition of her waking thoughts. Petrarch invokes the beauty of Laura. Eloisa, separated from Abelard, is again happy in his company, even amid the "dreary wastes" and "low-browed rocks."
There can be no doubt that the dreams of many persons are very greatly influenced by the reflections and emotions they have experienced the preceding day; but this is by no means invariably the case. We have known persons whose dreams refer habitually to events which occurred to them, perhaps, twenty years ago, and upon whom recent events seem to possess no such influence. We have often been told by ladies happily and affectionately married, that while they were engaged, although their thoughts were naturally much set on their engagement, they never dreamed of their lovers. So, also, the father of a family, habitually impressed with a sense of his responsibility and affection toward his offspring, will sometimes dream often enough of his neighbor's children, but seldom or, perhaps, never, of his own. Try to dream on a given subject--resolve and fix the attention upon it--going to sleep, and no sooner are our eyelids closed, than fantastic fancy will conjure up the most opposite and incongruous imagery. We have heard this dream-problem explained by referring it to a principle of _antagonism_, which, waking or sleeping, may be observed in the animal economy. If a limb become fatigued by remaining too long in one position, it will be relieved by being thrown into the very opposite condition; if the eye fatigue itself by gazing intently on the disc of any bright color, and the eyelids close, the very opposite, or antagonistic color will be depicted upon the retina: in like manner, when our waking thoughts--in connection with the nerve matter, which is their material instrument--have exhausted their energy, we can easily conceive how the very opposite condition will be produced. Hence the most unconnected and preposterous train of imagery may arise from the very earnestness with which we desire a contrary effect. We dream of events which do not concern us, instead of those in which we are most deeply interested; we dream of persons to whom we are indifferent, instead of those to whom we are attached. But, in the midst of all this curious and perplexing contrariety, it is remarkable--and may be esteemed a proof of the immateriality of the mind--that we always preserve the consciousness of our own identity. No man dreams that he is a woman, or any other person than himself; we have heard of persons who have dreamed they were dead, and in a spiritual state; but the spirit was still their own--they maintained their identity. Sir Thomas Lawrence once made an interesting observation on this subject to Mrs. Butler--then Miss Fanny Kemble: he pointed out, in conversation, that he never heard of any lady who ever dreamed that she was younger than she really was. We retain in our dreams even the identity of our age. It has been said--we think by Sir Thomas Browne--that some persons of virtuous and honorable principles will commit, as they fancy, actions in their dreams which they would shudder at in their waking moments; but we can not believe that the identity of moral goodness can be so perverted in the dreaming state. We can, however, readily conceive that, when the mind is oppressed, or disturbed by the recollection of some event it dreads to dwell upon, it may be disturbed by the most terrific and ghastly images. A guilty conscience, too, will unquestionably produce restlessness, agitation, and awe-inspiring dreams. Hence Manfred, in pacing restlessly his lonely Gothic gallery at midnight, pictures to himself the terrors of sleep: