'Phædrus. There is shade there, and the wind is not too strong, and there is grass to sit, or, if we like, to lie down. Socrates. Lead on, then.

'Phædrus. Tell me, Socrates, is it not from some part of the Ilissus hereabouts that Boreas is said to have carried off Oreithyia ?

'Socrates. So the story goes.

'Phædrus. Surely then this is the very spot. For the waters seem so lovely and pure and transparent, and as if made for girls to play on the bank.

Socrates. No, it is two or three stadia further down, where you cross over to the Temple of Agra. There you find somewhere an altar of Boreas.

'Phædrus. I was not aware of this: but tell me, by Zeus, O Socrates, dost thou believe this myth to be true ?' This is the introduction to an enquiry into the truth of mythology.

In the Platonic Dialogues, Sublimity, Pathos, Poetic Beauty, Humour, are produced by turns, as in a poem; while their avowed purpose is to ascertain philosophic truth. The crossquestioning operation of Socrates is exhibited upon a great variety of opponents; and the debate is interrupted by dramatic displays of personal feeling.

30. The chief scope for extraneous interest is in the choice of examples and illustrations.

Among the Platonic arts of exposition we must include examples and similes, which often excite other emotions than those belonging to science. The painful effect of the crossquestioning interrogation of Socrates, is compared to the shock of the Torpedo. Again, Socrates represents himself as seeking the good of his fellow-citizens, and not captivating them by showy arts; and hence, if brought to trial for his conduct, he would be like a physician arraigned by the confectioner before a jury of children.

The ass of Buridan-held in suspense between the equal attractions of two bundles of hay,-is an immortal illustration of the equipoise of motives in the human will. The humorous representation, already quoted from Carlyle (p. 133), of George II., in 1741, is an extension of this figure.

Paley's famous simile of the pigeons, in illustration of the nature of private property, is calculated to gratify the invidious sentiment felt towards the holders of property by those that have none,—an emotion altogether extraneous to science.

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Locke's affecting illustration of the fading of our recollections is given in Extract II.

The sentiment of Wonder is often appealed to.

The antiquarian interest of Geology is highly stimulating. Slight occasions of personal feeling will arise in the driest expositions. An allusion to a great discoverer, an expression of esteem or of contempt, of approbation or of disapprobation, of sympathy with the learner's difficulties, will impart unction and give a passing relief to the tension of the mind.

31. With regard to the employment of Illustrations for expository ends, the conditions and limitations already prescribed, under Figures of Similarity (p. 7), are fully applicable.

If the illustrations are sought exclusively for the sake of clearness, that is, if the ends of feeling and fancy are set aside, there is little danger of a wrong choice; the suitability must be evident to any one that attends to the matter. It is under the pressure of the extraneous motive of general human interest, that darkening illustrations are had recourse to.

In the best scientific writings, illustrations of a highly figurative nature are brought in only at considerable intervals; the exposition being chiefly made up of Iteration, Example, &c.

The due medium is thought to be realized in many of the dialogues of Plato, although in regard to some, the critics of his own country, whose taste on such a point was consummate, have charged him with excess.

The following short paragraph from Dr. Whewell has been praised as a specimen of philosophic style. It begins with a statement, follows up with an example, and closes with a happy illustration.

The type-species of every genus, the type-genus of every family, is, then, one which possesses all the characters and properties of the genus in a marked and prominent manner. The type of the Rose family has alternate stipulate leaves, wants the albumen, has the ovules not erect, has the stigmata simple, and besides these features, which distinguish it from the exceptions or varieties in its class, it has the features which make it prominent in its class. It is one of those which possess clearly several leading attributes; and thus, though we cannot say of any one genus that it must be the type of the family, or of any one species that it must be the type of the genus, we are still not wholly to seek; the type must be connected by many affinities with most of the others of its group;

it must be near the centre of the crowd, and not one of the stragglers.'

The next extract is a paragraph from Mr. Samuel Bailey, expounding the great principle of the remission or alternation of pleasures. It proceeds by Iteration, Examples, and Illustrations, and will reward a careful study.

'Wit and humour, it must be allowed, may be sometimes out of place, and sometimes carried to excess. This, however, is a liability which they share with other excellent things, and cannot be brought as a specific objection against them, although it may be against the works in which they appear. Enjoyment of every kind must, of course, have intermission; and the more exquisite the pleasure, the more is a suspension required. We sicken at perpetual lusciousness; we loathe the unvarying atmosphere of a scented room, although "all Arabia breathes from its recesses. "The breath of flowers," as Bacon beautifully observes, "is far sweeter in the air, when it comes and goes like the warbling of music, than in the hand." Even the rich illustrations which fancy scatters over the page of the orator or the poet, may be crowded on each other too fast. In eloquence, in fiction; in poetry, in every work intended to yield high and permanent pleasure, the body of the work must undoubtedly be something solid, something addressed to good sense or earnest feeling. The figurative decorations must appear no more than elegant foliage, or beautiful convolutions, surrounding the steadfast columns of thought and sentiment. Poets of mere imaginative power, however dazzling, who have not possessed considerable strength of intellect, have never been able to keep a high place in public estimation. For a while we are pleased to rise above the earth, and wing our way through the atmosphere of fancy; but we soon grow weary of an excursion which is all flight. In defiance of Bishop Berkeley, we must have a world of selid matter to alight and repose on.'

32. V. By calling attention to the special difficulties of the matter expounded.

It may be of the greatest use to show the precise difficulties that an exposition is intended to meet; an interest is aroused, and the ingenuity is put on the alert to judge of the attainment of the end proposed. Paley, in the preface to his Moral Philosophy, remarks:

'Concerning the principle of morals, it would be premature to speak; but concerning the manner of unfolding and explaining

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that principle, I have somewhat which I wish to be remarked. An experience of nine years in the office of a public tutor in one of the universities, and in that department of education to which these sections relate, afforded me frequent occasions to observe, that, in discoursing to young minds upon topics of morality, it required much more pains to make them perceive the difficulty, than to understand the solution; that, unless the subject was so drawn up to a point, as to exhibit the full force of an objection, or the exact place of a doubt, before any explanation was entered upon-in other words, unless some curiosity was excited before it was attempted to be satisfied, the labour of the teacher was lost. When information was not desired, it was seldom I found retained. I have made this observation my guide in the following work; that is, upon each occasion, I have endeavoured, before I suffered myself to proceed in the disquisition, to put the reader in complete possession of the question; and to do it in a way that I thought most likely to stir up his own doubts and solicitude about it.'

It requires a special explanation of incommensurable quantity, to make a pupil disposed to follow Euclid's definition of Proportionals.

The Socratic cross-questioning operation resulted in a painful sense of ignorance, which was the best preparation for the attainment of real knowledge.

33. VI. The Proof of a principle indirectly contributes to its exposition.

In the first place, the mere iteration or expansion incident to the proving of a doctrine is a means of impressing it.

In the next place, by seeing what the proofs are able to establish, we have a check upon the meaning and extent of the principle.

Thirdly, it is an additional advantage when the proof is made to include the statement and disproof of the counter proposition or propositions; as happens in a well-conducted polemical exposition.

The methods of Proof fall under Logic. They are either Inductive or Deductive; the one is proof from Facts, the other from the application of some higher or more general Law. That cloven-footed animals are herbivorous can be proved only by induction; that the path of a comet is a conic section can be proved deductively as well as inductively.

It would often contribute to clearness of exposition to

arrange the proofs of a fact or doctrine according to their logical method. Thus under Induction, it has been shown by Mr. J. S. Mill that there are four modes of bringing facts to bear upon the proof of a general proposition; he calls them the Four Experimental Methods (Agreement, Difference, Concomitant Variations, Residues). If there are any facts under Agreement, they might be stated first and apart; next those under Difference, and so on. To these Experimental or Inductive Proofs would follow the Deductive, or the assigning of the higher generality that includes under its sweep what is to be proved. See PERSUASION.

The Four methods imply the possibility of establishing a point as certain. In a vast number of instances, however, and many of them of the highest importance, the evidence is only probable. Here, too, Logical method would be of great service. Probable evidence is usually a concurrence of separate probabilities, each having an assignable value; the summing of them up being a well understood Arithmetical process. The good order, whether for Proof or for Exposition, would lie in first stating and appreciating the distinct probabilities, and then combining the sum into a joint probability.

Exposition by Proof is a part of Persuasion, and is named Argument.

34. VII. Inferences, Deductions, Corollaries, Applications, Consequences, may be drawn from principles, and may serve still farther to elucidate them.

To turn a principle to immediate account by deductive applications, necessarily engages our interest in it, while having the same efficacy as the proofs in expanding it to the mind, and in determining its precise import. The corollaries of a geometrical proposition contribute to clear up and impress the proposition; and the like holds all through science, and through the less scientific generalities.

Thus the First Law of Motion is practically applied to the beating out of dust, and to the drying of a mop: and these are good as examples in expounding the principle.

The doctrine of the Expansion of Bodies by heat has a wide range of applications, both to the unravelling of difficult phenomena, as the winds, and to processes in the arts.

The constitution of the Council and the Agora in early Greece is expounded by Grote with reference to its consequences, in the following paragraph:

'There is yet another point of view in which it behoves us