On the Origin of Species By Means of Natural Selection by Charles Darwin - Chapter 1 Part 1

Causes of Variability - Effects of Habit - Correlation of Growth - Inheritance - Character of Domestic Varieties - Difficulty of distinguishing between Varieties and Species - Origin of Domestic Varieties from one or more Species - Domestic Pigeons, their Differences and Origin - Principle of Selection anciently followed, its Effects, Methodical and Unconscious Selection - Unknown Origin of our Domestic Productions - Circumstances favourable to Man's power of Selection