pubOne.info present you this new edition. In the two preceding lectures I have endeavoured to indicate to you the extent of the subject-matter of the inquiry upon which we are engaged; and now, having thus acquired some conception of the Past and Present phenomena of Organic Nature, I must now turn to that which constitutes the great problem which we have set before ourselves; - I mean, the question of what knowledge we have of the causes of these phenomena of organic nature, and how such knowledge is obtainable.