134 THE PRINCIPLES OF SELF-MASTERY
Everyone needs a change of mental environment at regular periods,
the same as a change and variety of food are essential. The mind becomes
more alert, more elastic, and more ready to work with speed and accu-
racy after it has been bathed in new ideas, outside of one's own field of
daily labor.
As a student of this course you will temporarily lay aside the set
of ideas with which you perform your daily labors and enter a field of
entirely new (and in some instances, heretofore unheard-of) ideas.
Splendid! You will come out, at the other end of this course, with a
new stock of ideas that will make you more efficient, more enthusiastic,
and more courageous, no matter in what sort oj work you may be engaged.
Do not be afraid of new ideas. They may mean to you the differ-
ence between success and failure. Some of the ideas introduced in this
course will require no further explanation or proof of their soundness
because they are familiar to practically everyone. Some of the other ideas
introduced here are new, and for that very reason many students of
this philosophy may hesitate to accept them as sound.
I have thoroughly tested every principle described in this course,
and the majority of the principles covered have been tested by scores of
scientists and others who were quite capable of distinguishing between
the merely theoretic and the practical.
For these reasons all principles here covered are known to be work-
able in the exact manner claimed. However, no reader of this book is
asked to accept any statement made in these lessons without having first
satisfied himself or herself. by tests, experiments, and analysis, that the
statement is sound.
The major evil you are requested to avoid is that of forming opin-
ions without definite facts as the basis, which brings to mind Herbert
Spencer's famous admonition: ''There is a principle which is a bar against
all information; which is proof against all argument; and which cannot
fail to keep a man in everlasting ignorance. This principle is contempt
prior to examination:'