In a manner more familiar perhaps in music than in poetry Shelley is echoing another poem, borrowing, as it were, Milton’s voice though not his words, making in fact a musical quotation, a poetical allusion of an exquisite felicity. But by so doing he is necessarily restricting the number of the readers who will fully appreciate him. Such allusions are a normal and regular part of the resources of all poets who belong to the literary tradition, that is to say, of the vast majority of poets in modern times. They are not often so unobtrusive and the place which they are given in the structure of the poem varies. Sometimes, as in this instance, a failure on the part of the reader has no important consequences. One familiar with the _Hymn on the Morning of Christ’s Nativity_ will respond more fully and with a deeper sense of the situation; but a reader unfamiliar with it is not deprived of any major part of the poem. In other cases the loss is more serious. Another instance from Shelley will illustrate this, and it is interesting for its own sake. The Shape which guides the Chariot in the _Triumph of Life_ is described and identified for the reader in a large degree through another Miltonic quotation or allusion: A Shape So sate within, as one whom years deform, Beneath a dusky hood and double cape, Crouching within the shadow of a tomb, And o’er what seemed the head a cloud-like crape Was bent. Shelley, it is known, crystallised much of his philosophy in the sentence: ‘Death is the veil which those who live call life’, and the reference[72] here to the guardian of Hell Gate, What seem’d his head The likeness of a Kingly Crown had on, is not accidental or unimportant for the understanding of the poem.