Sir David Brewster (1781-1868) was a distinguished scientist and inventor who frequently turned the results of his research to practical ends; his work on the diffraction of light, for example, led to his developing improved reflectors for lighthouses and inventing two popular Victorian toys, the stereoscope and the kaleidoscope. He was also active as the editor of the Edinburgh Magazine and the Edinburgh Encyclopaedia (1808-1830) and contributed to the seventh and eighth editions of the Encyclopaedia Britannica, as well as writing many articles for a variety of philosophical and scientific journals. He was deeply religious, and in More Worlds Than One (1854) he set out to counter the arguments against extra-terrestrial life of William Whewell’s recently published Of the Plurality of Worlds (also reissued in this series), urging that Whewell’s ‘extraordinary doctrine’ was wrong on scientific grounds.