t to you, and
before you know it you are off in a long day-dream leading far from the
history lesson. Such migrations as these are very likely to occur in
study, and constitute one of the most treacherous pitfalls of student
life. In trying to avoid them, you must form habits of disregarding
irrelevant ideas when they try to obtrude themselves. And the way to do
this is to school yourself so that the first lapse of attention will
remind you of the lesson in hand. It can be done if you keep yourself
sensitive to wanderings of attention, and let the first slip from the
topic with which you are engaged remind you to pull yourself back. Do
this before you have taken the step that will carry you far away, for
with each step in the series of associations it becomes harder to draw
yourself back into the correct channel.

In reading, one frequent cause for lapses of attention and for the
intrusion of unwelcome ideas is obscurity in the material being read.
If you trace back your lapses of attention, you will often find that
they first occur when the thought becomes difficult to follow, the
sentence ambiguous, or a single word unusual. As a result, the meaning
grows hazy in your mind and you fail to comprehend it. Naturally, then,
you drift into a channel of thought that is easier to follow. This
happens because the mental stream tends to seek channels of least
resistance. If you introspect carefully, you will undoubtedly discover
that many of your annoying lapses of attention can be traced to such
conditions. The obvious remedy is to make sure that you understand
everything as you read. As soon as you feel the thought growing
difficult to follow, begin to exert more effort; consult the dictionary
for the meanings of words you do not understand. Probably the ordinary
freshman in college ought to look up the meaning of as many as twenty
words daily.

Again, the thought may be difficult to follow because your previous
knowledge is deficient; perhaps the discussion involves some fact which
you never did comprehend clearly, and you will naturally fail to
understand something built upon it. If deficiency of knowledge is the
cause of your lapses of attention, the obvious remedy is to turn back
and study the fundamental facts; to lay a firm foundation in your
subjects of study.

This discussion shows that the conditions at time of concentrated
attention are very complex; that the mind is full of a number of
things; that your object