every object etSwXa (or images) of the object are continually being given off in all directions ; these enter the organs of sense, and give rise to sensation. The rest of the theory remarkably anticipates certain famous modern theories of perception (1) by its reduction of all sensation, on the objective side, to touch, and (2) by the distinction which it involves between the qualities of extension and resistance, which are said to be the only qualities that really belong to objects of sense, and the other (or secondary) qualities, which are said to exist only through the action of the organs of sense modifying the eiScoAa. Sensation, Democritus appears to have taught, is our only source or faculty of knowledge; indeed his first prin ciples admit the existence of no mental faculty of a nature distinct from sensation. He was classed among the most extreme sceptics of antiquity, -and tradition attributes to him such sayings as " There is nothing true, and if there is, we do not know it," "We know nothing, not even if there is anything to know." The system of Democritus was altogether anti-theological. He denied that the creation of the world was in any way due to reason. He also rejected all the popular mythology ; but, according to one account, he taught that, as men were produced by the motion of the atoms, so was produced a race of grander beings, of similar form, and, though longer- lived, still mortal, who influence human affairs, some benevolently, some malevolently, and who appear to men in dreams. The moral system of Democritus is strikingly like the negative side of the system of Epicurus. The summum bonum is placed in an even tranquillity of mind. Fear, and too strong desire, and all that is likely to bring sorrow or even care, are to be avoided, as, for example, notably mar riage, to which Democritus cherished the strongest objec tions. This habit of mind Democritus is said to have himself so well attained that the merry spirit with which he re garded all that happened earned him the title of " the laughing philosopher." Another version, however, asserts that he received the name on account of the scorn which he poured on human ignorance and weakness. See Mullach, Democriti Abderitce operum fragmenta, Berlin, 1843; Franck, " Fragments qui subsistent de Democrite," in the Memoires de la Societe royale de Nancy, 1836 ; Ritter, Geschichte der Philosophic, vol. i. ; Brandis, Rhein. Museum, vol. iii., and Geschichte der Gricch und Rom Philosophic, vol. i. ; H. Stephanas, Poesis Philos. ; Burchardt, Commcniarin critica de Democriti de sensibus philosophia, 1839 ; and Fragmcntc der Moral dcs Dcmocrit.
DEMOIVRE, ABRAHAM (1G67-1754), an eminent
mathematician, was born at Vitry, in Champagne, May 26,
1667 He belonged to a French Protestant family, and
was compelled to take refuge in England at the revocation
of the Edict of Nantes, in 1685. Having laid the founda
tion of his mathematical studies in France, he prosecuted
them further in London, where he read public lectures on
natural philosophy for his support. The Principia Malhe-
matica of Newton, which chance threw in his way, made
him comprehend at once how little he had advanced in the
science which he professed ; but he pursued his studies
with vigour, and soon became distinguished among first-rate
mathematicians. He was among the intimate personal
friends of Newton, and his eminence and abilities secured
his admission into the Royal Society of London, and after
wards into the Academies of Berlin and Paris. His merit
was so well known and acknowledged by the Royal Society
that they judged. him a fit person to decide the famous con
test between Newton and Leibnitz. The life of Demoivre
was quiet and uneventful. His old age was spent in
obscure poverty, his friends and associates having nearly
all passed away before him. He died at London, Novem
ber 27, 1754. The Philosophical Transactions of London
contain several of his papers, all of them interesting. He
also published some excellent works, such as Miscellanea,
Analytica de Seriebus et Quadraturis, 1730, in 4 to. This
then contained some elegant and valuable improvements on
then existing methods, which have themselves, however, long
been superseded. But he has been more generally known
by his Doctrine of Chances, or Method of Calculating
the Probabilities of Events at Play. This work was first
printed in 1618, in 4to, and dedicated to Sir Isaac Newton.
It was reprinted in 1738, with great alterations and im
provements ; and a third edition was afterwards published
with additions. He also published a Treatise on Annuities,
1724, in 8vo, dedicated to Lord Carpenter.
DEMONOLOGY. The word demon (or daemon] is the
Greek [Greek], the etymology of which is too doubtful to
explain its original signification (see Pott, Etym. Forsch.,
ii. 1, 947). Setting aside the use of the word in the
general sense of deity (as in Iliad, i. 222), we find it
employed in classic Greek literature with the more specific
meaning under which it becomes an important term in the
science of religion. Among the most instructive passages
are those in which Hesiod tells how the men of the golden
race became after death demons, guardians or watchers
over mortals (Hesiod, Op. et Dies, 109, &c.; see Welcker,
Griech. Gotterlehre, vol. i. p. 731), and where the doctrines
of Empedocles, Plato, and other philosophers are set forth,
showing how the demons came to be defined as good and
evil beings intermediate between gods and men (Plutarch,
De Defect. Orac., De hid. et Osir., De Vitand. ^r. Alien.,
&c. ; Plato, Symposion, 28 ; Diog. Laert., Vit. Pythag. ; see
Grote, History of Greece, vol. i. chaps. 2, 17). The religions
of the world usually recognize an order of spiritual beings,
below the rank of governing deities, and distinguished from
nature-spirits such as elves and nymphs by being especially
concerned with living men and their affairs ; these beings,
very often themselves considered to be ghosts of dead men,
are the demons. The earlier and wider notion of demons
includes the whole class of such spirits, who may be friendly
or hostile, good or evil, persecuting and tormenting man or
acting as his protecting and informing patron-spirits ; while,
when they are mediators or ministers of some higher deity,
they will be, like the god himself, kindly or ill-disposed.
A narrower definition was introduced in Christian theology,
where the ideas of a good demon and guardian genius were
merged in the general conception of good " angels," while
the term demon was appropriated to evil spirits, or
" devils." For scientific purposes, it is desirable to use
the term in the wider sense. Demonology, the branch of
the science of religion which relates to demons, is much
obscured in the treatises of old writers by their taking the
evidence too exclusively from among civilized nations, and
neglecting what is to be learnt from barbarous tribes, whose
ideas of demons, being nearer their primitive state, are
comparatively clear and comprehensible. When savage
notions of the nature and functions of these spirits are
taken as the starting-point, the demon appears as only a
more or less modified human soul whether it is still
actually considered to be a human ghost, or whether part
of the human quality has fallen away, so that only traces
are left to show that man s soul furnished the original
model. But when such early and natural animistic concep
tions were carried on into higher stages of culture, their
original use as explaining natural phenomena was gradually
superseded by the growth of knowledge, and they came to
be maintained as broken-down and confused superstitions,
only to be understood by comparison with their earlier
forms. Such comparison, however, is facilitated by the
primitive demon-ideas cropping up anew even in civilized
life, as in the so-called " spirit-manifestations " of the
present day. The following details will show the main
