In 1849, at forty years of age—his voyage on the HMS Beagle behind him but the publication of The Origin of Species still to come—Darwin advised those who would follow in his footsteps to “acquire the habit of writing very copious notes, not all for publication, but as a guide for himself.” The naturalist must take “precautions to attain accuracy,” he continued, “for the imagination is apt to run riot when dealing with masses of vast dimensions and with time during almost infinity.”
