The philosophical system of Plato; dialectics. Locke maintains that the mind is by nature a sheet of white paper, the five senses being the doors of knowledge. Plato maintained the opposite theory, drawing a strong line of demarcation between the province of thought and that of sensations in the production of ideas.
It is characterised by the doctrine of pre-existing eternal ideas, and teaches the immortality and pre-existence of the soul, the dependence of virtue upon discipline, and the trust worthiness of cognition. In theology, he taught that there are two eternal, primary, independent, and incorruptible causes of material things—God the maker, and matter the substance.
In psychology, he maintained the ultimate unity and mutual dependence of all knowledge. In physics, he said that God is the measure of all things, and that from God, in whom reason and being are one, proceed human reason and those “ideas” or laws which constitute all that can do called real in nature.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894