ng pastoral peoples, when they, for
instance, changed their base of operation; but in its most complete
form migration occurred only after man had reached the stage of
agriculture.

If migration is a reasoned affair, it then follows that for every
migration there must be some definable cause. This cause must be a
very powerful one, because man is inclined to become attached to the
locality in which he finds himself placed. There are formed ties of
various kinds which tend to hold him to his home. These are the ties
of family, friendly associations, customs and habits of the community,
politics, religion, business, property, and superstitious reverence
for graves. His life is, therefore, closely bound up with his
surroundings, and the changing of it for that of another locality is a
matter of serious concern. Thus, "there is a marked inertia, a
resistance to pressure among human beings, and the presumption is that
people will stay where they are unless some positive force causes them
to move."

Furthermore, the force which operates in causing men to move generally
presents one of two aspects, viz., attractive and repellent. "Men are
either drawn or driven to break the ties which bind them to their
native locality." Again, the causes of migration are classified as
positive advantages and satisfactions, and negative discomforts and
compulsions. The causes of the repellent or negative type exist in the
environment of the locality to which man is already attached. They,
therefore, are much more important than the others, because, despite
the inducements of another locality which may be opened to him, it is
the tendency of man to remain where he is, if he is contented. These
forces must produce dissatisfaction with existing conditions in order
to induce man to move. The causes of the attractive or positive type,
on the other hand, are in a foreign environment, and operate often by
stimulating dissatisfactions through comparison. They must, before
movement can be induced, show that conditions in the new locality are
superior to those in the home environment. "Thus, in almost every case
of migration one is justified in looking for some cause of a repellent
nature, some dissatisfaction, disability, discontent, hardship, or
other disturbing condition;" and, likewise, some positive advantage,
satisfaction, prospect of contentment, or other favorable condition.
Therefore, it goes almost without saying that the study of this
subj