made a digest of all the works of Aristotle, which
proved to be easier for students than the originals, and which were
sometimes used in place of them. Among mathematical works of this
century were the _Algorismus_ (Arithmetic) and the _Libellus de Sphaera_
(On the Sphere) by John Holywood (Sacrobosco); and the _Perspectiva
Communis_, i.e. Optics, by John (Peckham) of Pisa. A treatise on Music
by John de Muris of Paris was produced in the early part of the
fourteenth century. All of these were well-known university text-books.
They appear in the list at Leipzig throughout the fifteenth century (see
p. 139).

4. UNIVERSITY PRIVILEGES

The privileges granted by civil and ecclesiastical powers constitute a
fourth important influence upon the growth of universities. Beginning
with the year 1158 a long series of immunities, liberties, and
exemptions was bestowed by State and Church upon masters and students as
a class, and upon universities as corporations. Masters and scholars
were, for example, often taken under the special protection of the
sovereign of the country in which they were studying; they were exempted
from taxation, and from military service; most important of all, they
were placed under the jurisdiction of special courts, in which alone
they could be tried. Universities as corporations were given, among
other privileges, the right to confer upon their graduates the license
to teach "anywhere in the world" without further examination, and the
very important right to suspend lectures, i.e. to strike, pending the
settlement of grievances against State or Church. They had, of course,
the general legal powers of corporations. Thus fortified, the
universities attained an astonishing degree of independence and power;
and their members were enabled to live in unusual liberty and security.
This fact in itself unquestionably tended to increase the university
population.

The masters and scholars of Bologna, Paris, and Oxford seem to have led
the way in securing privileges. Their precedent made it easier for later
universities to secure similar rights. These were sometimes established
"with all the privileges of Paris and Bologna," or "all the privileges
of any other university."

The authorities who granted privileges were the sovereigns of Various
countries,--the Emperor of the Holy Roman Empire, the kings of France,
England, the Spains--feudal lords, municipalities, and the Pope or his
legates. They usually con