Fleming was a
vitalist who was strongly opposed to
materialism. He believed that a 'vital principle' was inherent in the embryo with the capacity of "developing in succession the destined plan of existence." He was a close associate of
Robert Edmond Grant, who considered that the same laws of life affected all organisms. In 1821, he took part in a Northern Lighthouse cruise with
Robert Stevenson. They visited
Scalpay, Outer Hebrides. Murdo MacLellan of Scalpay gave them a live
Great auk, recently caught by four fowlers on St Kilda. Fleming describes this event in his "A History of British Animals" giving the year as 1822, though
John Alexander Smith confirm the correct year was 1821 in correspondence with
Thomas Stevenson. The Great Auk was allowed to swim in the sea tethered by a line attached to a leg, and it escaped from the line near the
Isle of Arran. This was the last Great Auk recorded in Britain, although a controversial account of a bird killed as a witch on St Kilda in the 1840s is also claimed as the last record. In 1824, Fleming became involved in a famous controversy with the geologist
William Buckland about the nature of
the flood as described in the Bible. In 1828, he published his
History of British Animals. This book addressed both extant and
fossil species. It explained the presence of fossils by climate change, suggesting that extinct species would have survived if weather conditions had been favorable. These theories contributed to the advancement of
biogeography, and exerted some influence on
Charles Darwin. Fleming's comments on instinct in his book
Philosophy of Zoology had also influenced Darwin. In 1831, Fleming found some fossils which he recognized as fish in the
Old Red Sandstone units at
Fife. This did not fit the generally accepted notion that the Earth was approximately 6,000 years old. == Works ==