o build up, and would be a wrong procedure.

You should _begin_ with specific training of particular sets of _sensory
muscles_ because, as we have seen, that is the _natural_ order of the
process of growth. It is how you began to learn everything you know. You
can increase and improve your present limited, conscious knowledge most
effectively by taking into your mind from your _trained_ particular
senses _more and better_ impressions than you ever have taken in before.

[Sidenote: Developing Persistence]

Suppose your success has been hindered by your lack of persistence. You
need to develop _that quality_ in particular. Let us see how the
discriminative-restrictive principle should be applied specifically to
assure you of building _persistence_ within yourself.

First it is necessary that you discriminate between _this one_ quality
and _all others_; especially between it and the quality of
_determination_. Very _different_ training methods are required to
develop persistence and determination respectively. When you are just
"determined" to do a thing, your jaw muscles, your arm and back muscles,
perhaps all your commonly known muscles, will be hardened _as long as
you remain determined, but no longer_. They will relax when the occasion
for determination has passed. The habit of instantly tensing your
muscles temporarily whenever you need to be determined will very greatly
strengthen and improve the efficiency of your brain-mind center of
_determination._ But that _temporary_ hardening of your muscles will
only slightly affect the development in you of _characteristic
persistence_.

[Sidenote: Developing Determination]

Hence the training of your muscles for building the habit of
determination within you should be concentrated on exercise in _changing
swiftly_ from comparative laxity to _muscular tension_. That is, in
order to accustom your _mind_ to hardening with _determined thoughts_
whenever determination is needed, you should train your _muscles_ to
harden _in coordination_, and thus to support your mental determination
by the complementary _physical suggestion_ of the same quality.

You do not need to use determination _all the time_; so it will be
sufficient if your muscles are taught to be _quickly responsive_ to
determination of mind on any occasion. (You know it helps you to carry
out a resolution if you stiffen your body at the moment you make up your
mind to do a thing, but _continued_ stiffness of th