THERE are two states of mind that peculiarly illustrate attention and dissociation as complementary processes. These two states of mind also offer interesting and indisputable evidence of the facts we have placed before you. One of these states of mind is the condition known as abstraction or absorption. The other is sleep. Both are simply degrees of limitation of the field of consciousness.

During our waking moments there are times when the dissociative faculty and conversely and consequently the attention as an emphasizing agency are more active than at other times. The degrees of this activity range from the most intense absorption in the business in hand to the sort of relaxed daydreaming in which we allow our thoughts to wander here and there at the call of every association that incoming sense-impressions or a capricious reproduction of memory pictures may arouse. In each type all the senses may be awake, but in the former the attention, like a watchful sentinel, is alert to guard the mind of consciousness against all sensory impressions not provided with the countersign of relevancy, while in the latter the sentinel himself seems asleep and the dream palace of consciousness is open to every chance impression.

The profound concentration of the attention, amounting to abstraction or absorption, is peculiarly characteristic of persons of unusual mental power.

As a matter of fact, it would seem that this phenomenon is in no sense an absence of mind, but is merely a concentration of the mental forces upon one subject to the exclusion of all else. Many anecdotes are related of Sir Isaac Newton, illustrating his so-called "absence of mind." On one occasion, when he was giving a dinner to some friends, he left the table to get them a bottle of wine. On his way to the cellar he became lost in reflection on some philosophic problem, forgot his errand and his company, and was soon hard at work in his study.

So Archimedes, when the Romans captured Syracuse, was so absorbed in his mathematical researches that he heard nothing of the noise and tumult that accompanied the taking of the city. Suddenly a soldier entered the philosopher's room and ordered him to go into the street. Archimedes, lost in thought, ignored the command, and the soldier in a rage plunged his sword into the philosopher's body.

It is told of the poet Lessing, that one evening upon arriving at his door he absent-mindedly inquired of the servant if her master was at home. Receiving a negative reply, he said he would call again and walked away, much to the servant's mystification.

Sir William Hamilton tells us that "the mathematician Vieta was sometimes so buried in meditation that for hours he bore more resemblance to a dead person than to a living one, and was then wholly unconscious of everything going on around him. On the day of his marriage, the great Bud-daeus forgot everything in his philological speculations, and he was only awakened to the affairs of the external world by a tardy embassy from the marriage party, who found him absorbed in the composition of his "Commentarii.' "

These classical instances have their counterparts to a greater or less degree in the lives of every one of us. Who has not at some time had the experience of suffering great pain from some accident or illness until so diverted by the humorous conversation of friends, or perhaps by some exasperating incident arousing his wrath, as to no longer be aware of even the slightest feeling of discomfort? Yet, when the incident came to an end, the pain would return. A soldier in the heat of battle has been known to hurl himself forward to the charge, knowing nothing of the fact that he had received his death-wound.

All these things show how, in the stress of profound mental activity or intense emotional excitement, the attention refuses to admit to consciousness sense-impressions which at another time would be of compelling interest. Under such circumstances, the senses continue mechanically to register impressions, and these impressions continue to be stored away in subconsciousness, perhaps to surprise us at some future day. Consciousness only is restricted to a narrow field.

The same principle is illustrated by the manner in which the mind disregards those familiar sense-impressions which by experience it knows to be of no interest. The business man in his downtown office does not even hear the roar of traffic on the street. But if he is compelled to return to work at his desk at night he will at once mark the unusual stillness. Throughout the day his senses had faithfully reported the street noise to his mind, but his discriminating attention had vigilantly diverted them from consciousness.

The countryman newly arrived in a great city gawks about, all eyes and ears. Almost every sense-impression means to him something new and strange or beautiful. Yet in a short time these things cease to interest him, until, in the midst of the city's turmoil, he is able to become absorbed in conversation with a friend.

The whispered sound of one's own name will attract his attention amid a babel of loud voices. The rumble of a passing street-car will be unperceived by one who will nevertheless be annoyed by the hum of a mosquito.

In all these cases a feeble sensation is allowed to become active in consciousness and is perceived with great clearness, while a throng of much stronger sensations occurring at the same time is forced to pass unnoticed. The hum of the mosquito is as nothing compared to the noise of the passing car, yet the car goes by unperceived.

Is it possible, then, that the light and sound vibrations coming from these external objects first awaken the senses, and that the senses then arouse the consciousness? Not at all: the senses and consciousness were all awake and active all the time, and they received these ether vibrations and disposed of them; hut that part of the mind called consciousness, and capable of looking in upon its own operations, was concerned with only a small part of the news that was received.