The question need not concern us beyond the fact that the thinking of our most wakeful moments perpetually plays into our subconscious life. In order that the flow of thought welling up from the deepest depths of the soul may be clear, copious, and full, it is the duty of the teacher to keep himself and his pupils wide awake during the hours of study and recitation. He should not worry them by excessive tasks or unreasonable examinations so that the hours of sleep are disturbed by dreams, followed during the day by weariness and fatigue. The folly of burning the midnight oil and of spending too many hours each day in mental toil is fraught with evil consequences in the domain of thought. In the main Harbaugh was right when he undertook to change Franklin’s maxim about early rising into the following form: “Go to bed early, and get up late; but then keep awake all day.”
Thought like a stream.
So far as we are aware, thought is going forward continuously while we are awake. This phase of consciousness has been likened to a stream, and has given rise to the expression, The stream of thought. The metaphor can be pressed very far without conveying untruths. A stream does not always flow with the same velocity. It is at times deep, at other times shallow, now moving forward like a swollen torrent, now flowing placidly with scarcely a wave or a ripple perceptible on its surface. Here its smooth course is disturbed by wind and storm and rain; there its even flow is influenced by rocks and irregularities in the bed of the stream. Again and again its current is modified by affluents which empty their waters into the main stream, perhaps changing the appearance from clear to cloudy or muddy, or, it may be, exerting the opposite effect. To all these peculiarities in the flow of the stream there are likenesses in the stream of thought. At times it is deep and at other times shallow, now violent and disturbed, now calm and placid, sometimes clear to the bottom, sometimes cloudy, yea, muddy, always modified more or less by influences from without, which are taken up into the main current of thought and alter the stream like the tributaries of a great river.
Early life.
Other metaphors.
On reaching the level country a river may spread out into a lake, resulting in a clearing up of the water and resembling the periods of calm meditation during which the soul clarifies its thinking. The lifelike behavior of rivers and the carving of land forms from their youth through maturity to old age have furnished many a figure of speech for our poetic literature. The change from the active upper waters to the sedate lower current may typify the change in the stream of thought as we pass from youth to age. While the volume of the stream is small and the channel lacks depth, it is easy to change the direction of the current, as sometimes happens when a straight channel is dug to take the place of its windings. In early life the stream of thought is apt to wander in meandering courses; the teacher may very frequently find it necessary to keep the mind from wandering, to direct the stream of thought towards the destined goal, and to make it groove for itself channels in harmony with logical habits. In teaching pupils to think it is quite as essential to give direction to thought as it is to furnish either thought-stimulus or thought-material. In one respect the metaphor, stream of thought, fails utterly to express the truth. The constituents of thought are not related to each other like the molecules of a liquid which move freely among themselves. Thoughts have a connection with those that precede and those that follow. An inner nexus binds the successive portions of a demonstration. Hence other figures of speech have been employed to denote the connection between the successive elements of a logical proof, such as the train of thought, the line of argument, the chain of reasoning.
Cognitive function.
It will be readily admitted that often our thinking is so loose and disjointed that its component parts resemble the liquid more than the chain, whereas our best thinking—namely, that which leads to a goal in the shape of a trustworthy conclusion—resembles a train of cars in which motive power is derived not from steam, but from a conscious expenditure of will-power. The teacher may perform the triple function of fireman, engineer, and switch-tender, supplying the fuel for the process, regulating the speed, and directing it along the lines of track which lead to the desired goal. It is as natural for a pupil to think as it is for a stream to flow towards the ocean. The stream may run shallow if no supply of water is received from the outside. It is the mission of the teacher to keep up the supply, to remove as far as possible the obstructions which are likely to throw the current of thought into unexpected channels. It is a peculiarity of this current of thinking that it is cognitive, or possesses the function of knowing. Human thought resembles the stream in seemingly taking up and carrying what was not a part of itself. Just as the stream of water carries minerals in solution as well as silt, sand, pebbles, and even heavier objects, so the stream of thought appears to lay hold of objects and to carry them as part of itself. Here, however, the strings of the analogy break. The stream of thought is in the mind; the objects with which it deals are outside of the mind. Mental pictures of these objects float in the stream of thought as objects on the bank of a river are mirrored in its waters; yet the parallel is not complete, because the mind may turn the eye upon itself and make what is thus seen the object of thought. This turning upon itself may be likened to eddies in the stream. But even when the mind thus turns back upon itself and views its own states and activities, these are regarded as objective, as related to the thinking process very much like the objects of knowledge in the external world.
Another important phase of thinking finds no likeness in any of the figures of speech above referred to. The mind meets certain objects of thought on which it seems to tarry or fasten itself. This has led some writers to deny that the stream of thought is a continuous current. This view causes undue stress to be laid upon the material of thought, and leads the teacher to undervalue his function as directing guide in teaching pupils to think. Even Professor Bain claims that,—