to west, which lasted for centuries. The
migrations of the Middle Ages ever affect individual classes alone; the
knights in the crusades, the merchants, the wage-craftsmen, the
journeymen hand-workers, the jugglers and minstrels, the villeins
seeking protection within the walls of a town. Modern migrations, on the
contrary, are generally a matter of private concern, the individuals
being led by the most varied motives. They are almost invariably without
organization. The process repeating itself daily a thousand times is
united only through the one characteristic, that it is everywhere a
question of change of locality by persons seeking more favorable
conditions of life.

Among all the phenomena of masses in social life suited to statistical
treatment, there is without doubt scarcely one that appears to fall of
itself so completely under the general law of causality as migrations;
and likewise hardly one concerning whose real cause such misty
conceptions prevail.

The whole department of migrations has never yet undergone systematic
statistical observation; exclusive attention has hitherto been centered
upon remarkable individual occurrences of such phenomena. Even a
rational classification of migrations in accord with the demand of
social science is at the present moment lacking.

Such a classification would have to take as its starting-point the
result of migrations from the point of view of population. On this basis
they would fall into these groups: (1) migrations with continuous change
of locality; (2) migrations with temporary change of settlement; (3)
migrations with permanent settlement.

To the _first_ group belong gypsy life, peddling, the carrying on of
itinerant trades, tramp life; to the _second_, the wandering of
journeymen craftsmen, domestic servants, tradesmen seeking the most
favorable spots for temporary undertakings, officials to whom a definite
office is for a time entrusted, scholars attending foreign institutions
of learning; to the _third_, migration from place to place within the
same country or province and to foreign parts, especially across the
ocean.

An intermediate stage between the first and second group is found in the
_periodical migrations_. To this stage belong the migrations of farm
laborers at harvest time, of the sugar laborers at the time of the
_campagne_, of the masons of Upper Italy and the Ticino district, common
day-laborers, potters, chimney-sweeps, chestnut-roasters,