Facsimile of a page from a note-book of 1837, by Charles Darwin. Transcription (from source): “led to comprehend true affinities. My theory would give zest to recent & Fossil Comparative Anatomy : it would lead to study of instincts, heredity, & mind heredity, whole metaphysics, it would lead to closest examination of hybridity & generation, causes of change in order to know what we have come from & to what we tend, to what circumstances favour crossing & what prevents it, this & direct examination of direct passages of structure in species, might lead to laws of change, which would then be main object of study, to guide our speculations.” — from the Life and Letters of Charles Darwin, edited by his son Francis Darwin, in Two Volumes: Vol. II. New York: D. Appleton and Company, 1887.