In the study of poetry, Arnold delineates his idea of excellent poetry and formulates a practical method for identifying the true poetry -this method is named by him the Touchstone method. According to this method the specimens of the very highest quality of poetry are compared to the specimens of the work of poetry under study and conclusions are drawn in favour or against the work. This method requires to keep in ones mind lines and expressions of the great masters, and apply them as a touchstone to other poetical works.
In order to find the truly excellent poetry, we should form a real estimate of poetryl as opposed to "historical estimate "and personal estimate “. Both historical and personal estimates go in vein. He argues us not to be misled by the historic and personal estimates while judging poetry. Arnold says than the personal estimate should be eschewed because it will lead to wrong judgments. The historic estimate or judging a poet from the point of view of his importance in the course of literary history is also not a true judgment of a poet. Its historical importance may make us rate the work as higher than it really deserves. "the course of development of a nation's language, thought, and, poetry is profoundly interesting, and by regarding a poet’s work as a stage in this course of development, we may easily bring ourselves to make it of more importance as poetry than in itself it really is." Arnold gives a concrete example of the fallacies of the historical approach. Caedmon's position is important in the historical sense but it would be wrong to hold him in the same level as Milton poetically because of this historical position.
Arnold offers his theory of touchstone method to form a real estimate of poetry in distinguishing a real classic from a dubious classic and form a real estimate of poetry; one should have the ability to distinguish a real classic. He says "a dubious classic, let us shift him; if he is a false classic, let us explode him . But he is a real classic, if his works belong to the class of the very best, then the great thing for us to feel and enjoy his work as deeply as ever we can." A best classic is recognized by placing it beside the known classics of the world. Those known classics can serve as the touch stood by which the merits of contemporary poetic work can be tested. This is the central idea of Arnold's touchstone method.
Arnold suggests that a reader should always have in his mind lines and expressions of the great masters of poetry and that these lines should be applied as touchstone to judge other poetry. The poetry need not resemble these lines and expressions, they may be very different applied with fact and care, can help us "detect the presence or absence of high poetic quality and also the degree of this quality, in all other poetry which we may place beside them ".
Arnold illustrates his point in giving short passages and even single lines from Homer, Dante, Shakespeare, and Milton as models for judging the order of excellence in a modern poet or a work. These are Arnold’s touchstones gathered from the work of the greatest classics of European literature in his time. He gives Shakespeare’s lines of Henry the fourth's expostulation with sleep
"Wilt thou upon the high and giddy mast
Seal up the ship boy's eyes, and rock his brains
In cradle of the rude imperious surge . . .”
Then Miltonic passage
"Darken'd so ,yet shone
Above them all the archangel; but his face
Deep sears of thunder had intrench’d, and care
Sat on his faded check . . ."
“And courage never to submit or yield
And what is else not to be overcome . . ."
Arnold believes that even a single line if it is good would do: “In la sua volun tade e nostra pace".
Arnold shows this how this method is to be made use of . He first quotes few lines from Chaucer and says Chaucer is found to be lacking of high seriousness. By using one line from Dante ,"In la sua volun tade e nostra pace" as a touchstone and by comparing Chaucer 's line with that he concludes that "the substance of Chaucer 's poetry ,his view of things and his criticism of life ,has largeness ,freedom shrewdness ,benignity, but it has not this high seriousness"
Arnold applies the touchstone method for determining the worth of the works of Dryden and Pope and comes to the conclusion that though they can be called the classics of poetry .And also taking lines from Chaucer
"My throat is cut Unto my nekke-bone
Saide this child, and as by way of kinde
I should have deyd,yea,longe time agone;” as a touchstone and by comparing with some lines of
“My throat unto the bone I trow ,
said this young child ,and by the law of kind
I should have died yea, many hours ago" he concludes that the charm of Chaucer’s lines are most attractive than Wordsworth.
Again Arnold has used touchstone method by comparing Dryden with Milton "When we find Milton writing :And long it was not after, when I was confirmed in this opinion, that he, who would not be frustrate of his hope to write well hereafter in laudable things, ought himself to be a true poem,...it is obsolete....” But when Dryden tells us: "what Virgil wrote in the vigour of his age, in plenty and at ease, I have undertaken to tramplkt in my declining years." Then we find Dryden is a true English prose writer.”
We see that Arnold had introduced a very novel and practical device to detect the order of excellence on a given poem. Explaining this method we can find that "there can be no mare useful help for discovering what poetry belongs to the class of the truly excellent, and can therefore do us most good, than to have always in one's mind lives and expressions of the great masters and to apply them as a touchtone to other poetry."