"As a man thinketh in his heart so is he," is a saying which is
invariably true where the sight is concerned. When a person remembers
or imagines an object of sight perfectly the sight is perfect; when he
remembers it imperfectly the sight is imperfect. The idea that to do
anything well requires effort, ruins the sight of many children and
adults; for every thought of effort in the mind produces an error of
refraction in the eye. The idea that large objects are easier to see
than small ones results in the failure to see small objects. The fear
that light will hurt the eyes actually produces sensitiveness to
light. To demonstrate the truth of these statements is a great
benefit.

Remember a letter or other object perfectly, and note that the sight
is improved and pain and fatigue relieved; remember the object
imperfectly, and note that the vision is lowered, while pain and
fatigue may be produced or increased.

Rest the eyes by closing or palming, and note that the vision is
improved, and pain and discomfort relieved; stare at a letter,
concentrate upon it, make an effort to see it, and note that it
disappears, and that a feeling of discomfort or pain is produced.

Note that a small part of a large object is seen better than the rest
of it.

Accustom the eyes to strong light; learn to look at the sun; note that
the vision is not lowered but improved, and that the light causes less
and less discomfort.

Remember your successes (things seen perfectly); forget your failures
(things seen imperfectly); patients who do this are cured quickly.