The Wonders of Life is a classic and venerable biology text and "a popular study of biological philosophy" by Ernst Haeckel that examines the merits of evolution theory and the origins of life. The publication of the present work on The Wonders of Life has been occasioned by the success of The Riddle of the Universe, which I wrote five years ago. Within a few months of the issue of this study of the monistic philosophy, in the autumn of 1899, ten thousand copies were sold.