PLATO, 
632 
of actions, it is pradical. Theoretical philofophy pro¬ 
duces a contemplative life, in which the mind, occupied 
in meditations purely intellectual, acquiresa refemblance 
to the divinity. Practical philofophy leads to an a&ive 
life, and applies the principles of wifdom to the benefit 
of fociety. Befides the contemplation of truth and 
virtue, the philofopher will enquire into the right con- 
dud of the underftanding, and the powers of fpeech ; or 
will ftudy the art of reafoning and difputation. The 
office of philofophy then is threefold ; dialedlic, theoreti¬ 
cal, and practical. 
On Dialectics, the fum of Plato’s doClrine, as colle&ed 
from his Dialogues, is this : Truth is difcerned, not by 
the fenfes, but by the underftanding. The human intel¬ 
lect is employed, either upon things which it compre¬ 
hends by itfelf, and which are in their nature fimple and 
invariable, or upon things which are fubjedt to the fenfes, 
and which are perpetually liable to fluctuation and 
change. The contemplation of the former creates 
jcience ; attention to the latter produces opinion. Senfe 
is the paffive perception of the foul through the medium 
of the body. When the forms of things are, by means 
of the corporeal organs, fo deeply impreffed upon the 
mind as not to be eafily effaced by time, this permanent 
imprefiion is called memory. From the union of fenfe 
and memory, or from the companion of the prefent with 
a recolle&ed perception, arifes opinion. Where thefe 
agree, the opinion is true; where they differ, it is falfe. 
Tiie feat of perception and memory is like a waxen tablet, 
or picture, which the mind contemplates, and then 
frames opinions. In meditation, the foul converfes with 
itfelf; thought flows through the lips by means of the 
vocal organs. IntelleCtion is the operation of the under¬ 
ftanding contemplating intelligent forms or ideas. It is 
twofold : the firft, that of the foul contemplating ideas 
before it defcends into the body; the other, that which 
it exercifes after it is immerfed in the body, which may 
be alfo termed natural knowledge. This kind of know¬ 
ledge confifts in the recolleCIion of thofe things which 
the mind had known in, its pre-exiftent ftate, and differs 
from memory in the objeCl; memory being employed 
upon fenfible things, reminifcence upon things purely 
intelligible. The intelligible objeCIs of contemplation 
are either primary or fecondary; the primary are ideas, 
which will be farther explained under the next head; the 
fecondary, are the forms infeparable from material ob¬ 
jeCIs. The mind, in exercifing its judgment, confiders 
theoretically what is true or falfe, and praCtically what 
may, or may not, be done. Dialedics conlider the 
effence and the accidents of things; concerning the 
former, it makes life of divifion, definition, and analyfis. 
Divifion feparates the genus into its fpecies, the whole 
into its parts, and the like. Definition expreffes the 
genus of the thing to be defined, and diftinguifnes it 
from all others by adding its fpecific difference. Analyfis 
rifes from the objects ot fenfe to intelligibles; from de- 
monftrable propofitions to axioms, or from hypothefis to 
experience. Induction rifes from individuals to univer- 
fais. Syllogifm produces a conclufion by means of fome 
intermediate propofttion. Thefe topics are curioully 
touched upon by Plato ; and it is rather by examples than 
by precepts, that he teaches the true, art of reafoning, or 
expofes the fallacies of fophiftry. The ingenious arti¬ 
fices and deceptions praCtifed by the fophilt are clearly 
reprefented in feveral of Plato’s dialogues, particularly in 
his Euthydemus and his Sophifta. Rhetoric is an art 
which Plato thought unfavourable to the ftudy of philo- 
fopliy: he inveighs againft it with great vehemence in 
his Georgias; and the ground of his invedive is judi- 
cioufly explained by Quintilian. (Inft. Orat. 1 . ii. c. 15.) 
Etymology is a fubjeCton which Plato particularly treats 
in his Cratylus, in.which he maintains, that names, when 
rightly given, correfpond to the nature of things which 
they represent: but what he advances on this head is too 
fanciful to merit attention. 
Theoretical Philofophy Plato divides into three branches, 
theological, phyfical, and mathematical. On Theology , 
the fundamental doCtrine of Plato, as of all other ancient 
philofophers, is, that from nothing nothing can proceed. 
This univerfal axiom, applied not only to the infinite 
efficient, but to the material, caufe, Plato, in his Timteus, 
lays down as the ground of his reafoning concerning the 
origin of the world. In this Dialogue, which compre¬ 
hends his whole dodlrine on the fubjeft of the formation 
of the univerfe, matter is fo manifeftly fpoken ofas eter¬ 
nally co-exifting with God, that this part of his dc&rine 
could not have been miftaken by fo many learned and 
able writers, had they not been feduced by the defire of 
eftablifhinga coincidence of doftrine between the wri¬ 
tings of Plato and Mofes. It is certain that neither 
Cicero, nor Apuleius, nor Alcinous, nor even the later 
commentator Chalcidius, underftood their mafter in any 
other fenfe, than as admitting two primary and incorrupt¬ 
ible principles, God and matter; to which we fhall after¬ 
wards fee reafon to add a third, namely ideas. The paf- 
fages quoted by thofe who maintain the contrary opinion 
are by no means fufficient for their purpofe. Matter, ac¬ 
cording to Plato, is an eternal and infinite principle. 
His doClrine on this head is thus explained by Cicero ; 
(Acad. Quell. 1 . i. c. 8.) “ Matter, from which all things 
are produced and formed, is a fubftance without form or 
quality, but capable of receiving all forms, and undergo¬ 
ing every kind of change ; in which, however, it never 
fuft’ers annihilation, but merely a folution of its parts, 
which are in their nature infinitely divifible, and move in 
portions of fpace which are alfo infinitely divifible. When 
that principle which we call quality is moved, and a&s upon 
matter, it undergoes an entire change, and thofe forms 
are produced, from which arifes the diverfified and cohe¬ 
rent fyftem of the univerfe.” This doClrine Plato 
unfolds at large in his Timteus, and particularly infills 
upon the notion, that matter has originally no form, but 
is capable of receiving any. He calls it the mother and 
receptacle of forms, by the union of which with matter 
the univerfe becomes perceptible to the fenfes; and 
maintains, that the vifible world owes its forms to the 
energy of the divine intelleftual nature. It is eafy to 
perceive, that Plato’s account of matter is eflentially dif¬ 
ferent from that which fuppofes it to confift of fmall 
indivifible particles, and confequently that Plato is not 
to be ranked among the atomic philofophers. Another 
conception refpedting matter, which arifes from the pre¬ 
ceding, is, that matter is not body, but that from which 
bodies are formed. “ Body is that which is produced 
from matter by the energy of the efficient caufe.” This 
diftindtion is found in almoft all the ancient fyftems of 
philofophy : it is therefore neceflary, in examining them, 
not to underftand the terms incorporeal and immaterial 
as fynonymous. It was alfo a dodlrine of Plato, that there 
is in matter a neceflary, but blind and refractory, force; 
and that hence arifes a propenlity in matter to diforder 
and deformity, which is the caufe of all the imperfection 
which appears in the works of God, and the origin ot 
evil. On this fubjedt Piato writes with wonderful obfcu- 
rity ; but, as far as we are able to trace his conception -i, 
he appears to have thought, that matter, from its nature, 
refills the will of the Supreme Artificer, fo that he cannot 
perfedlly execute his defigns; and that this is the caufe 
of the mixture of good and evil which is found in the 
material world. 
The principle oppofite to Matter, in the fyftem of 
Plato, is God. He taught, that there is an Intelligent 
Caufe, which is the origin of all fpiritual being, and the 
former of the material world. The nature of this great 
Being he pronounced it difficult to difcover, and, when 
difcovered, impoffible to divulge. The exiftence of God 
he inferred from the marks of intelligence which appear 
in the form and arrangement of bodies in the vifible 
world: and from the unity of the material fyftem he 
concluded, that the mind by which it was formed mull 
