The Sand Walk near Down House, Darwin's thinking path.

"Sandwalk or sand walk. Path running around a small wood on the southeast corner of the grounds of Down House where CD took his daily walk. It took this name from a sandpit at the south end used for dressing the path. Also known as CD's "thinking path", however a source for CD calling it this has not been found. He did call it the "path". 1846 CD rented the 1½ acres from J.W. Lubbock for £1 12s per annum. See CD to J.W. Lubbock [16 Jan. 1846], CCD3:276. CD planted it with hazel, alder, lime, hornbeam and birch, with a dogwood privet and fence along the exposed side. 1855 His observations on plants growing along the sandwalk led to 'Vitality of Seeds' (Shorter publications, F1686). There was eventually a summer-house at far southeast end. ED2:76. An outing to the sandwalk by the convalescing Henrietta was noted in ED's diary in 1861. CD's number of circuits when he was ill was also noted by ED, with "4 times Sandwalk" meaning CD was feeling better. 1874 CD purchased it at the high price of £300. After his death, May 7 ED went in bath chair. The next day she walked there with Horace. ED may have taken her last walk in 1896 Jul. 19. CD took his last walk there on 7 Mar. 1882 when he experienced a seizure and made it back to the house with difficulty. LL3:357. Gwen Raverat's recollection of it is very detailed, Raverat, Period piece, 1952, p. 156. See Atkins 1974, pp. 25-6. 1996 paved by English Heritage to support larger numbers of visitors."

From the richest volume on Darwin ever published: Darwin: A Companion, 2021.

See: The Complete Photographs of Darwin