Another important subject is also treated in the Phædrus. Sokrates delivers views both original and characteristic, respecting the efficacy of continuous discourse--either written to be read, or spoken to be heard without cross-examination--as a means of instruction. They are re-stated--in a manner substantially the same, though with some variety and fulness of illustration--in Plato's seventh Epistle[125] to the surviving friends of Dion. I have already touched upon these views in my eighth** Chapter, on the Platonic Dialogues generally, and have pointed out how much Plato understood to be involved in what he termed _knowledge_. No man (in his view) could be said to know, who was not competent to sustain successfully, and to apply successfully, a Sokratic cross-examination. Now knowledge, involving such a competency, certainly cannot be communicated by any writing, or by any fixed and unchangeable array of words, whether written or spoken. You must familiarise learners with the subject on many different sides, and in relation to many different points of view, each presenting more or less chance of error or confusion. Moreover, you must apply a different treatment to each mind, and to the same mind at different stages: no two are exactly alike, and the treatment adapted for one will be unsuitable for the other. While it is impossible, for these reasons, to employ any set forms of words, it will be found that the process of reading or listening leaves the reader or listener comparatively passive: there is nothing to stir the depths of the mind, or to evolve the inherent forces and dormant capacities. Dialectic conversation is the only process which can adapt itself with infinite variety to each particular case and moment--and which stimulates fresh mental efforts ever renewed on the part of each respondent and each questioner. Knowledge--being a slow result generated by this stimulating operation, when skilfully conducted, long continued, and much diversified--is not infused into, but evolved out of, the mind. It consists in a revival of those unchangeable Ideas or Forms, with which the mind during its state of eternal pre-existence had had communion. There are only a few privileged minds, however, that have had sufficient communion therewith to render such revival possible: accordingly, none but these few can ever rise to knowledge.[126] [Footnote 125: Plato, Epistol. vii. pp. 341-344.] [Footnote 126: Schleiermacher, in his Introduction to the Phædrus, justly characterises this doctrine as genuine Sokratism--"die ächt Sokratische erhabene Verachtung alles Schreibens and alles rednerischen Redens," p. 70.] [Side-note: Written matter is useful as a memorandum for persons who know--or as an elegant pastime.]