In 1890 I gave a lecture to the Edinburgh Health Society, which appeared as No.2 of their Eleventh Series. Its title is “The Importance of Ideals of Health, Beauty, etc., in Race Progress.”

Much the same thesis considerably expanded was given by me in the form of three Milroy Lectures to the Royal College of Physicians of London in March, 1894, and appeared at the time almost verbatim in the Lancet.

The present volume contains these lectures somewhat arranged to suit a less technically instructed audience. I am indebted to my colleague, Professor Richards, for his kindness and care in revising the proofs.