The essential principle of his versification is to let sentences, prolonged and articulated as freely and naturally as in prose, wind their way in and out among the rimes, the full pause often splitting a couplet by falling at the end of the first line, and oftener still (in the proportion of two or three times to one) breaking up a single line in the middle or at any point of its course. Sense and sound flow habitually over from one couplet to the next without logical or grammatical pause, but to keep the sense of metre present to the ear Keats commonly takes care that the second line of a couplet shall end with a fully stressed rime-word such as not only allows, but actually invites, at least a momentary breathing-pause to follow it. It is only in the rarest cases that he compels the breath to hurry on with no chance of stress or after-rest from a light preposition at the end of a line to its object at the beginning of the next ('on | His left,' 'upon | A dreary morning'), or from an auxiliary to its verb ('as might be | Remembered') or from a comparative particle to the thing compared ('sleeker than | Night-swollen mushrooms'); a practice in which Chapman, Ben Jonson, Fletcher, and their contemporaries indulged, as we have seen, freely, and which afterwards developed into a fatal disease of the metre. Keats's musical and metrical instincts were too fine, and his ear too early trained in the 'sweet-slipping' movement of Spenser, to let him fall often into this fault. To the other besetting fault of some of these masters, that of a harsh and jolting ruggedness, he was still less prone. Although he chooses to forgo that special effect of combined vigour and smoothness proper to the closed couplet, he always knows how to make a rich and varied music with his vowel sounds; while the same fine natural instinct for sentence-structure as distinguishes the prose of his letters makes itself felt in his verse, so that wherever he has need to place a full stop he can make his sentence descend upon it smoothly and skimmingly, like a seabird on the sea.[1] The long passage quoted from Book III in the last chapter illustrates the narrative verse of _Endymion_ in nearly all its moods and variations. Here is a characteristic example of its spoken or dramatic verse. Endymion supplicates his goddess from underground:--