a man must concentrate.

The undecided man can not bring himself to a focus. He dissipates his
energy, scatters his forces, and executes nothing. He can not hold to
one thing long enough to bring success out of it. One vocation or
occupation presents its rosy side to him, he feels sure it is the thing
he wants to do, and, full of enthusiasm, adopts it as his life's work.
But in a few days the thorns begin to appear, his enthusiasm
evaporates, and he wonders why he is so foolish as to think himself
fitted for that vocation. The one which his friend adopted is much
better suited to him; he drops his own and adopts the other. So he
vacillates through life, captured by any new occupation which happens
to appeal to him as the most desirable at the time, never using his
judgment or common sense, but governed by his impressions and his
feelings at the moment. Such people are never led by principle. You
never know where to find them; they are here to-day and there
to-morrow, doing this thing and that thing, throwing away all the skill
they had acquired in mastering the drudgery of the last occupation. In
fact, they never go far enough in anything to get beyond the drudgery
stage to the remunerative and agreeable stage, the skilful stage. They
spend their lives at the beginning of occupations, which are always
most agreeable. These people rarely reach the stage of competency,
comfort, and contentment.

There is a legend of a powerful genius who promised a lovely maiden a
gift of rare value if she would go through a field of corn, and,
without pausing, going backward, or wandering hither and thither,
select the largest and ripest ear. The value of the gift was to be in
proportion to the size and perfection of the ear. She passed by many
magnificent ones, but was so eager to get the largest and most perfect
that she kept on without plucking any until the ears she passed were
successively smaller and smaller and more stunted. Finally they became
so small that she was ashamed to select one of them; and, not being
allowed to go backward, she came out on the other side without any.

Alexander, his heart throbbing with a great purpose, conquers the
world; Hannibal, impelled by his hatred to the Romans, even crosses the
Alps to compass his design. While other men are bemoaning difficulties
and shrinking from dangers and obstacles, and preparing expedients, the
great soul, without fuss or noise, takes the step, and lo, t