The Present Condition of Organic Nature / Lecture I. (of VI.), "Lectures to Working Men", at the Museum of Practical Geology, 1863, on Darwin's Work: "Origin of Species"

The lecture presents and defends the theory that species arise through variation and natural selection, explaining how heritable differences, competition for resources, and cumulative change produce adaptations and new forms. It reviews anatomical, embryological, and distributional evidence that links organisms by common descent, shows how classification mirrors genealogical relationships, and contrasts biological processes with inorganic phenomena. The speaker emphasizes observation, experiment, and critical reasoning in evaluating hypotheses, addresses common objections to evolutionary explanation, and frames scientific inquiry as a practical method for understanding the organic world rather than as appeal to authority.