“Science is the poetry of the intellect and poetry the science of the heart's affections.”

Part I : Contemporary Issues in Science, Ch. 1 : "The Scientist as Rebel"; this first appeared in New York Review of Books (25 May 1995).
The Scientist As Rebel (2006)
Context: There is no such thing as a unique scientific vision, any more than there is a unique poetic vision. Science is a mosaic of partial and conflicting visions. But there is one common element in these visions. The common element is rebellion against the restrictions imposed by the locally prevailing culture, Western or Eastern as the case may be. It is no more Western than it is Arab or Indian or Japanese or Chinese. Arabs and Indians and Japanese and Chinese had a big share in the development of modern science. And two thousand years earlier, the beginnings of science were as much Babylonian and Egyptian as Greek. One of the central facts about science is that it pays no attention to East and West and North and South and black and yellow and white. It belongs to everybody who is willing to make the effort to learn it. And what is true of science is true of poetry.... Poetry and science are gifts given to all of humanity.

Part 2: "The Habit of Truth", §6 (p. 36)
Science and Human Values (1956, 1965)

Lectures on Education delivered at the Royal Institution of Great Britain, London, 1855, published in "What Knowledge is of Most Worth", The Westminster Review (July 1859) volume CXLI, p. 1-23, at p. 19 http://books.google.com/books?id=5NQ6AQAAMAAJ&pg=RA1-PA19
Context: The current opinion that science and poetry are opposed is a delusion. … Think you that a drop of water, which to the vulgar eye is but a drop of water, loses any thing in the eye of the physicist who knows that its elements are held together by a force which, if suddenly liberated, would produce a flash of lightning? Think you that what is carelessly looked upon by the uninitiated as a mere snow-flake does not suggest higher associations to one who has seen through a microscope the wondrously varied and elegant forms of snow-crystals? Think you that the rounded rock marked with parallel scratches calls up as much poetry in an ignorant mind as in the mind of a geologist, who knows that over this rock a glacier slid a million years ago? The truth is, that those who have never entered upon scientific pursuits know not a tithe of the poetry by which they are surrounded.

Source: The Hero With a Thousand Faces

Part 1, LXXI
Meditations of a Parish Priest (1866)

Source: Infinite in All Directions (1988), Ch. 1 : In Praise of Diversity
Context: Science is not a monolithic body of doctrine. Science is a culture, constantly growing and changing. The science of today has broken out of the molds of classical nineteenth-century science, just as the paintings of Pablo Picasso and Jackson Pollock broke out of the molds of nineteenth century art. Science has as many competing styles as painting or poetry. The diversity of science also finds a parallel in the diversity of religion.

Von andern Seiten her vernahm ich ähnliche Klänge, nirgends wollte man zugeben, daß Wissenschaft und Poesie vereinbar seien. Man vergaß, daß Wissenschaft sich aus Poesie entwickelt habe, man bedachte nicht, daß, nach einem Umschwung von Zeiten, beide sich wieder freundlich, zu beiderseitigem Vorteil, auf höherer Stelle, gar wohl wieder begegnen könnten.
Zur Morphologie (On Morphology), (1817)

The Usurpation Of Language (1910)
Context: Though science makes no use for poetry, poetry is enriched by science. Poetry “takes up” the scientific vision and re-expresses its truths, but always in forms which compel us to look beyond them to the total object which is telling its own story and standing in its own rights. In this the poet and the philosopher are one. Using language as the lever, they lift thought above the levels where words perplex and retard its flight, and leave it, at last, standing face to face with the object which reveals itself.

Source: The Outermost House: A Year of Life On The Great Beach of Cape Cod