HUYGENS, Christiaan (1629-1695). The Celestial Worlds discover'd: or, Conjectures concerning the Inhabitants, plants and productions of the worlds in the planets. London: for Timothy Childe, 1698.

First edition in English of Huygens' Cosmotheoros, first printed in Latin that same year—the first serious exploration of the idea of extra-terrestrial life. Huygens is perhaps best known for his studies on the rings of Saturn, but he was also a brilliant theoretician and engineer who brought a sparkling intellect to bear on a number of related fields. The present work, a Copernican treatise on life beyond our world, was composed not long before his death and only published posthumously. In it, Huygens speculates on the environmental conditions of other planets and their ability to support life, the possible nature of extraterrestrial beings, and the existence of other solar systems beyond our Sun.

While other authors had written fantastical tales about life on the Moon and other planets, Huygens specifically labels his work here as conjecture, rather than fiction—that is, not just fancies springing from the imagination, but a vision arising from use of the reason. The visualization of celestial objects and concepts not visible to the human eye was a crucial aspect of astronomy, which required scientists to extrapolate physical truths based on mathematical observations. Huygens's theorizing about the nature of life on other planets was simply an extension of this practice, using what could be observed of other planets in combination with logic to speculate on alien life—speculations which caught the imaginations of other thinkers, who were inspired in turn to look more closely at the heavens. John Flamsteed gave a copy of this book to Thomas Plume, a philanthropist who was moved to endow the Plumian Professorship of Astronomy and Experimental Philosophy at Cambridge, which still exists today. Wing H-3859.

Small quarto (170 x 107mm). 5 folding engraved plates (a few spots, very minute worming to lower margin at end). Contemporary paneled calf (rebacked, endpapers renewed, upper corner of front board clipped).