the sense of hearing must be on guard; so that no break of twig
or crash of bough can go unremarked. Rhinoceroses conceal
themselves most cannily, and have a deceitful habit of leaping
from a nap into their swiftest stride. Cobras and puff adders are
scarce, to be sure, but very deadly. Lions will generally give
way, if not shot at or too closely pressed; nevertheless there is
always the chance of cubs or too close a surprise. Buffalo lurk
daytimes in the deep thickets, but occasionally a rogue bull
lives where your trail will lead. These things do not happen
often, but in the long run they surely do happen, and once is
quite enough provided the beast gets in.

At first this continual alertness and tension is rather
exhausting; but after a very short time it becomes second nature.
A sudden rustle the other side a bush no longer brings you up all
standing with your heart in your throat; but you are aware of it,
and you are facing the possible danger almost before your slower
brain has issued any orders to that effect.

In rereading the above, I am afraid that I am conveying the idea
that one here walks under the shadow of continual uneasiness.
This is not in the least so. One enjoys the sun, and the birds
and the little things. He cultivates the great leisure of mind
that shall fill the breadth of his outlook abroad over a newly
wonderful world. But underneath it all is the alertness, the
responsiveness to quick reflexes of judgment and action, the
intimate correlations to immediate environment which must
characterize the instincts of the higher animals. And it is good
to live these things.