The same procedure may be used in the predicate calculus, but it
is complicated, tedious, and ugly. It is for this reason--plain
laziness, too--that the logiciain repairs to axiom schemata
instead of axioms when formalizing the predicate calculus. Axiom
schemata do not themselves appear in the formal system. They are
part of the logician's own vernacular, expressed in the same
language that he or she employs to talk about formulas and
predicate symbols. Each axiom schemata specifies the form of a
formula, and each axiom of the system itself is obtained from
the form as an instance. Source: The Advent of the Algorithm:
The 300-Year Journey from an Idea to the Computer, Pages: 73
Contributed by: Chris