Zeno of Elea, the friend and pupil of Parmenides, born 500 B.C., brought nothing new to the system, but invented _Dialectics_, the art of disputation,--that department of logic which afterward became so powerful in the hands of Plato and Aristotle, and so generally admired among the schoolmen. It seeks to establish truth by refuting error through the _reductio ad absurdum_. While Parmenides sought to establish the doctrine of the _One_, Zeno proved the non-existence of the _Many_. He did not deny existences, but denied that appearances were real existences. It was the mission of Zeno to establish the doctrines of his master. But in order to convince his listeners, he was obliged to use a new method of argument. So he carried on his argumentation by question and answer, and was therefore the first who used dialogue, which he called dialectics, as a medium of philosophical communication. Empedocles, born 444 B.C., like others of the Eleatics, complained of the imperfection of the senses, and looked for truth only in reason. He regarded truth as a perfect unity, ruled by love,--the only true force, the one moving cause of all things,--the first creative power by which or whom the world was formed. Thus "God is love" is a sublime doctrine which philosophy revealed to the Greeks, and the emphatic and continuous and assured declaration of which was the central theme of the revelation made by Jesus, the Christ, who resolved all the Law and the Gospel into the element of Love,--fatherly on the part of God, filial and fraternal on the part of men.