“Ye Presences of Nature in the sky And on the earth! Ye Visions of the hills! And Souls of lonely places! can I think A vulgar hope was yours when ye employed Such ministry, when ye through many a year Haunting me thus among my boyish sports, On caves and trees, upon the woods and hills, Impressed upon all forms the characters Of danger or desire; and thus did make The surface of the universal earth With triumph and delight, with hope and fear, Work like a sea?...” In thus citing Wordsworth, the point which I wish to make is that we forget how strained and paradoxical is the view of nature which modern science imposes on our thoughts. Wordsworth, to the height of genius, expresses the concrete facts of our apprehension, facts which are distorted in the scientific analysis. Is it not possible that the standardised concepts of science are only valid within narrow limitations, perhaps too narrow for science itself? Shelley’s attitude to science was at the opposite pole to that of Wordsworth. He loved it, and is never tired of expressing in poetry the thoughts which it suggests. It symbolises to him joy, and peace, and illumination. What the hills were to the youth of Wordsworth, a chemical laboratory was to Shelley. It is unfortunate that Shelley’s literary critics have, in this respect, so little of Shelley in their own mentality. They tend to treat as a casual oddity of Shelley’s nature what was, in fact, part of the main structure of his mind, permeating his poetry through and through. If Shelley had been born a hundred years later, the twentieth century would have seen a Newton among chemists. For the sake of estimating the value of Shelley’s evidence it is important to realise this absorption of his mind in scientific ideas. It can be illustrated by lyric after lyric. I will choose one poem only, the fourth act of his _Prometheus Unbound_. The Earth and the Moon converse together in the language of accurate science. Physical experiments guide his imagery. For example, the Earth’s exclamation, “The vaporous exultation not to be confined!” is the poetic transcript of ‘the expansive force of gases,’ as it is termed in books on science. Again, take the Earth’s stanza, “I spin beneath my pyramid of night, Which points into the heavens,—dreaming delight, Murmuring victorious joy in my enchanted sleep; As a youth lulled in love-dreams faintly sighing, Under the shadow of his beauty lying, Which round his rest a watch of light and warmth doth keep.”