This book is a collection of essays written by Thomas Henry Huxley, who is best remembered today for his impassioned defense of Charles Darwin's theories. Huxley himself is also a biologist and anthropologist, and this book shows his expertise in the form of his writings, as featured in the following selection of titles: 'The Present Condition of Organic Nature', 'Time and Life', and 'The Condition of Existence as Affecting the Perpetuation of Living Beings'.