Shakespeare, the introduction of unpoetical matter may be necessary for the sake of relief, or as a vivid expression of recondite conceptions, and (as it were) to make friends with the reader’s imagination. This necessity, however, cannot make the additions in themselves beautiful and pleasing. Sometimes, on the other hand, while we do not deny the incidental beauty of a poem, we are ashamed and indignant on witnessing the unworthy substance in which that beauty is imbedded. This remark applies strongly to the immoral compositions to which Lord Byron devoted his last years. Now to proceed with our proposed investigation. We will notice _descriptive poetry_ first. Empedocles wrote his physics in verse, and Oppian his history of animals. Neither were poets--the one was an historian of nature, the other a sort of biographer of brutes. Yet a poet may make natural history or philosophy the material of his composition. But under his hands they are no longer a bare collection of facts or principles, but are painted with a meaning, beauty, and harmonious order not their own. Thomson has sometimes been commended for the novelty and minuteness of his remarks upon nature. This is not the praise of a poet; whose office rather is to represent _known_ phenomena in a new connexion or medium. In _L’Allegro_ and _Il Penseroso_ the poetical magician invests the commonest scenes of a country life with the hues, first of a mirthful, then of a pensive mind.[21] Pastoral poetry is a description of rustics, agriculture, and cattle, softened off and corrected from the rude health of nature. Virgil, and much more Pope and others, have run into the fault of colouring too highly;--instead of drawing generalized and ideal forms of _shepherds_, they have given us pictures of _gentlemen_ and _beaux_. Their composition may be poetry, but it is not pastoral poetry. [21] It is the charm of the descriptive poetry of a religious mind, that nature is viewed in a moral connexion. Ordinary writers (e. g.) compare aged men to trees in autumn--a gifted poet will reverse the metaphor. Thus:-- ‘How quiet shows the woodland scene! Each flower and tree, its duty done, Reposing in decay serene, _Like weary men when age is won_,’ &c.