These assumptions which so densely obscure the issue raise innumerable practical difficulties both for criticism and for the construction of a theory of criticism. It is well worth while to analyse typical situations a little further. The closing lines of the Fifth Sonnet of Wordsworth’s River Duddon series will afford a convenient instance:— Sole listener, Duddon! to the breeze that played With thy clear voice, I caught the fitful sound Wafted o’er sullen moss and craggy mound, Unfruitful solitudes that seemed to upbraid The sun in heaven!—but now, to form a shade For thee, green alders have together wound Their foliage; ashes flung their arms around; And birch trees risen in silver colonnade. And thou hast also tempted here to rise, Mid sheltering pines, this cottage rude and grey; Whose ruddy children, by the mother’s eyes Carelessly watched, sport through the summer day, Thy pleased associates—light as endless May On infant bosoms lonely nature lies. Two readers who found themselves, as they thought, in entire agreement as to the excellence of this sonnet, and especially as to the beauty of its close, were surprised shortly afterwards to discover that they had been reading quite different poems. By the one the last sentence was interpreted as saying that the gloom of lonely nature, of sullen moss and craggy ground, however it might seem later on in life, had no oppressive effect upon the children. By the other it was read as saying that however barren and gloomy might be the scene, actually lonely nature there in itself had no such character, but was, as it were, floating “light as endless May on infant bosoms”. The two readings, by throwing their effect back upon what had preceded and in addition completely altering the rhythm of the close, produced what it is no exaggeration to describe as two different poems. Neither would be uncharacteristic of Wordsworth, although doubtless the first reading is the one to be accepted. This exemplifies what is perhaps the rarest case,[68] that in which agreement as to value covers an actual grave difference in the experiences valued. More usually there is some genuine source for the agreement, to be found in some common character of the experiences. What this common character is may be difficult to discover. It may be merely the rhythm, or the cadence of some phrase, or the form of a sequence of references. But sometimes, if it is a more obvious part, such as a description or metaphor, a discussion between critical readers, who are aware that their experiences differ, will bring it to light.