The central argument in "Principles" was that "the present is the key to the past" – a concept of the Scottish Enlightenment which David Hume had stated as "all inferences from experience suppose ... that the future will resemble the past", and James Hutton had described when he wrote in 1788 that "from what has actually been, we have data for concluding with regard to that which is to happen thereafter." Geological remains from the distant past can, and should, be explained by reference to geological processes now in operation and thus directly observable. Lyell's interpretation of geological change as the steady accumulation of minute changes over enormously long spans of time was a powerful influence on the young Charles Darwin. Lyell asked Robert FitzRoy, captain of HMS "Beagle", to search for erratic boulders on the survey voyage of the "Beagle", and just before it set out FitzRoy gave Darwin Volume 1 of the first edition of Lyell's "Principles". When the "Beagle" made its first stop ashore at St Jago in the Cape Verde islands, Darwin found rock formations which seen "through Lyell's eyes" gave him a revolutionary insight into the geological history of the island, an insight he applied throughout his travels.