That the mind should, merely because of the body's sleep, be able to _create_ a whole scene of a terrible drama with a rapidity impossible when all the functions are awake and active is incredible. The only function of the brain capable of this lightning-like swiftness of vision is _memory_. To create requires a certain effort, consumes a certain period of time, but a scene once beheld, an adventure once experienced and vividly impressed upon the memory, can be recalled in its minutest details in a period of time too short to be reckonable. That the sensitive plate of the brain never loses any clear picture once received, has been demonstrated beyond doubt. The picture, the sensation, may be overlaid and hidden for a long time beneath the heaps of useless lumber that the days and years accumulate in the mind's storehouse, but need or accident, or a similarity of circumstance, will bring the forgotten belonging to light--sometimes with startling effect. There is the well-known instance of a girl who, during an attack of fever delirium, spoke in a language that no one about her could understand. Investigation proved it to be Welsh--a language of which, both before and after her illness, she was totally ignorant. Further investigation showed that being born in Wales she had understood the tongue as a very little child, but had afterwards completely forgotten it. It is commonly known that in the struggle of the body against death by water, the memory, stirred to furious effort, produces all her stores at once--probably in the frantic endeavour to find some experience which may be of use in this crisis. It is often broadly asserted that the memory retains each and every experience which life has presented for its contemplation, but this is hardly true. The memory makes to a certain extent a choice, and chooses oftentimes with apparent caprice. To demonstrate the truth of this, let one endeavour to recall the first impression retained by his childish mind and it usually proves to be something extremely trivial. My own first clear memory is a sense of the comfort to my tired little two-year-old body of the clean linen sheets of the bed at the end of a perilous and adventurous journey, of whose startling incidents my memory preserved only one. Often this capricious faculty will seize upon some few high lights in a vivid picture and reject all the unimportant details. As a rule, however, it is the profound stirring of the emotions which wakes the memory to activity. A woman never forgets her first lover. A man to the end of his life can recall his first triumph, or his most imminent danger, and a trifle will often, after the lapse of half a century, fill the eye with tears, make the cheek burn, or the heart beat with the power of the long-passed emotion, preserved living and fresh by the memory.