s an evil influence, antagonistic
to God, involves a kind of dualism. But generally speaking this dualism
is permissive, inasmuch as it is always held that God will triumph over
Satan in His own time. So in Zoroastrianism the dualism is not ultimate,
for Ahriman and Ormuzd are represented as the twin sons of Zervana
Akarana, i.e. limitless time, wherein both will be finally absorbed. The
postulate of an Evil Being arises from the difficulty, at all times
acutely felt by a certain type of mind, of reconciling the existence of
evil with the divine attributes of perfect goodness, full knowledge and
infinite power. John Stuart Mill (_Essay on Religion_) preferred to
disbelieve in the omnipotence of God rather than forgo the belief in His
goodness. It follows from such a view that Satan is not the creation of
God, but rather a power coeval in origin, over whose activity God has no
absolute control.

_In Theology._--Dualism is also used in a special theological sense to
describe a doctrine of the Nestorian heresy. According to this doctrine
the personality of Christ is twofold; the divine Logos dwells as a
distinct personality in the man Jesus Christ, the union of the two
natures being analogous to the relation between the believer and the
indwelling Holy Spirit.

_History of the Doctrine._--The earliest European thinkers (see IONIAN
SCHOOL OF PHILOSOPHY) endeavoured to reduce all the facts of the
universe to a single material origin, such as Fire, Water, Air. It is
only gradually that there appears any recognition of a spiritual
principle exercising a modifying or causal influence over inert matter.
Anaxagoras was the first to postulate the existence of Reason ([Greek:
nous]) as the source of change and progress. Yet even he did not
conceive this Reason as incorporeal; it was in reality only the most
highly rarefied form of matter in existence. In Plato for the first time
we find a truly dualistic conception of the universe. Asserting that
Ideas alone really exist, he yet found it necessary to postulate a
second principle of not-being, the groundwork of sensuous existence and
of imperfection and evil. Herein he identified metaphysics and ethics,
combining the good with the truly existent and evil with the
non-existent. Aristotle rebels against this conception and substitutes
the idea of [Greek: prote hyle] and development. Nevertheless he does
not escape from the dualism of Form and Matter, [Greek: nous] and
[Greek: hyle].