The Idea of good is so called only in the Republic, but there are traces of it in other dialogues of Plato. It is a cause as well as an idea, and from this point of view may be compared with the creator of the Timaeus, who out of his goodness created all things. It corresponds to a certain extent with the modern conception of a law of nature, or of a final cause, or of both in one, and in this regard may be connected with the measure and symmetry of the Philebus. It is represented in the Symposium under the aspect of beauty, and is supposed to be attained there by stages of initiation, as here by regular gradations of knowledge. Viewed subjectively, it is the process or science of dialectic. This is the science which, according to the Phaedrus, is the true basis of rhetoric, which alone is able to distinguish the natures and classes of men and things; which divides a whole into the natural parts, and reunites the scattered parts into a natural or organized whole; which defines the abstract essences or universal ideas of all things, and connects them; which pierces the veil of hypotheses and reaches the final cause or first principle of all; which regards the sciences in relation to the idea of good. This ideal science is the highest process of thought, and may be described as the soul conversing with herself or holding communion with eternal truth and beauty, and in another form is the everlasting question and answer—the ceaseless interrogative of Socrates. The dialogues of Plato are themselves examples of the nature and method of dialectic. Viewed objectively, the idea of good is a power or cause which makes the world without us correspond with the world within. Yet this world without us is still a world of ideas. With Plato the investigation of nature is another department of knowledge, and in this he seeks to attain only probable conclusions (Timaeus).